Well I finally got around to making a few changes to the exhaust.

1.) I took out the stock rear mufflers and replaced them with a less restrictive Nitro muffler that has the same design as a Borla muffler but at a much cheaper price ($140 for both and that included installation).

This was not enough growl factor for me as the mufflers were just slightly louder then stock; (on a scale from 1 - 10 with 10 being the loudest) Id rate it at about a 3 rating and stock being a rating of 1.

2.) After a week or so of driving my car around and letting the fiber of the new muffler burn some;, I was not satisfied with the sound so I took it back to the muffler shop and had the front mufflers removed. This brought out a deeper tone out of the exhaust pipes which I would rate about a 5 in growl factor loudness. (Cost was $40 for removal of front mufflers replaced by 2.25 pipe/ I stayed with the under the axle stock pipes because I was afraid the straight pipes would scrape on speed bumps.

I am not a fan of super loud, noisy mufflers like those put on Mustangs and Camaros so these changes have me some what more satisfied then before but I am shooting for about an 7 in loudness and I am considering a crossover X pipe with the removal of the center muffler. I have not tested if this change has improved my mpg but I definately feel more of a kick out of the engine; especially at moderate speeds of over 50 mph. I have included some pics and when I get a chance I will upload a video of the sound for those interested..

 

Here's what I'm running. The center muffler is deleted with a crossover connection (stock CATS) and the rear mufflers have been deleted wth straignt pipes with 4" tips. I only have the small mufflers that are just before the rise over the rear axle. The sound is clearly V8 and on your scale would be a 5 at cruise and 9 on acceleration. I have a drone now at 2000 RPM that I hope to solve with a 24" closed resonator off each pipe. If that doesn't work I will install 2 smaller mufflers where the center muffler used to be.

 

Ya - I looked inside the front mufflers and they are basically just a box with no chambers inside and I didnt really see any vent with fibers inside either. From what I was told at the muffler shop, it sounds like the center muffler has the most flow restriction besides the stock rear mufflers.

I was also told that if you have too much straight pipe at a certain point you may get a flutter or popping type sound when letting go of the gas at certain rpms. Is that what you mean by the drone in the 2000 rpms?

The guy at the muffler shop also said that the cross pipe helps with equalization of the flow when you delete the center muffler.

Im sure those resonators will help if so. Thanks for sharing your setup Dave. Its good to know these things as we begin to personalize our cats...

 

No popping sounds. The drone is a resonant frequency based on the length of the exhaust system, exhaust temperature and the speed of sound. It sounds like a loud, constant musical note at a certain rpm. In my and most exhaust sytems it seems to happen at approximately 2000 rpm. The resonator is a dead end pipe that is tied into the current exhaust system and changes the length of the exhaust system (from the sound waves perspective) and will move up the drone to a higher frequency. If the drone moves to 3000 rpm you will not notice it since you don't stay at 3000 rpm for long. 2000 rpm on my XK8 puts me between 60 to 70 mph. At 75 mph I hear virtually nothing.

 

Interesting. Sounds like ur on the right track. Have u done any other mods ? I got a k& n air filter on mine. After I replace the front driver side ABS sensor, I'm gonna install Volo vp12 performance chip. I know there are many on this board that advised against it but it was only $90 plus I'm connecting via male obd II adapter to take it on and off when I'd like. What other performance mods are u planning Dave?

 

Please post a video with sound.
Thanks

 

Call me old but my recently acquired 97 XK8 has a Mina exhaust system which, in my opinion, is too loud and it sounds choppy at full throttle. I attribute this to the Mina system which doesn't have a crossover. The previous owner spent over $1000 for the Mina stuff including installation. Luckily he kept the original exhaust components so I might just have them re-installed. IMHO, a Jag shouldn't sound like it came out of the Fast and Loud shop! Why did Mina elect to go Under the rear axles? I get nervouse whenever I see a speed bump coming up.
BTW, I just ordered the secondary tensioners and gaskets today and will install them myself as soon as they arrive. The tensioners came from Kearny Ford in San Diego and the gaskets from BritishUK. Interestingly, the guy from the San Diego Ford store called me to inform that the tensioners would not be warranteed since they were going into a Jag, not a Lincoln.

 

I am looking to add a bit more of a growl and punch to my xk8. Any suggestions?

 

Any good custom exhaust shop can delete the rear muffler and straight pipe the rear for approx $160 including new tips. Keep the original mufflers for future sale if necessary. You will have a "manly" jag!
Dave

 

Update: I will be cutting out the center muffler on my Jag probably next week because I think I wouldnt mind just tad bit more of noise. I will be using a crossover in replacement of the center muffler. View my first post on what I have right now. Now the rest is a review of the performance chip I have installed.

I was skeptical about this because there are so many different products out there of this type. This product only had one review when I ordered it. I decided to give it a try anyway. So far I have driven 200 miles with the chip on and the product specifies that it recommends a 120 miles break in period. Before I forget, I got the plug and play version of this chip that directly plugs in via OBD II. You will have to connect two wires to the plug and my cars sequence was backwards from what was specified on the chips instructions. Just remember that pin 16 is the (red) positive and you can figure out the rest of the pin sequence from there. Anyway - I have not seen any mpg gains yet but maybe its too early. What I have seen is a a better average improvement in throttle response and definately a difference in torque. I have a modified exhaust system and K & N air filter and this thing works great with both of them. The car feels like its running much smoother as well and I still havent put new spark plugs on it. I have punched it a few times with and without the chip and by far it is a noticible difference with this thing on. I don't know how or why but I am definately a believer now. I can tell you that the exhaust upgrade just made a tad difference but this one is much more noticible. I will update if there is a drop or gain in performance/mpg as it is still too early to tell if this will last. One thing I must mentioned is that the company has great customer support as they exchanged the wired chip to the plug and play version with no questions asked and no extra charge.

 

The OBD II has two tabs which can be held down and removed from under the dash. I placed the chip and OBD II port in the fuse box compartment.

 

The two biggest flow restrictions are the OEM cat/downpipes and the over the axle bend. The center muffler isn't a valid restriction until these two parts of the exhaust are removed. All it really does is keep noise out of the cab. You can remove it and put an X or H pipe to get more rasp... on an KX8 the center muffler delete works well, but you do get some drone. On the XKR the center muffler delete has cabin drone and sounds horrid.

The fill in my Mina mufflers has been deadened and they're quite loud now. With the NP cats, a borla 2 in 2 out internal x pipe muffler and the Mina rears, I sound like a race car when I accelerate hard, but if I'm driving lightly, it has a nice and very distinct 'sporty' but not excessively loud note. But, if I floor it, you can hear it for blocks.

 

I really want hi flow cats but the cost is whats keeping me from buying. Id rather spend that money on updating my wheels from the revolver rims I have to something more modern. From what Ive read on the forums, the nameless hi flow cat brand run you about $900 bucks plus installation so thats easily over $1000 bones. Is there any other alternative to the nameless cats? Something that will not cause any sensor codes? Us XK8 owners dont have much options for increasing preformance like the XKR owners do. Thats primarily why I gave the volo chip a try.

 

Hmm - that Volo thing with a BMW on a dyno

With chip
Run #1: Max HP 265.71; Max Torque 291.78
Run #2: Max HP 265.93; Max Torque 291.79

Runs establish a good baseline, and are nearly identical with the chip installed.

Disconnected the chip from the power source and did one additional run under the same conditions as above:

Run #3: Max HP 267.56; Max Torque 295.17

I'm really rather surprised that it did anything at all (although I doubt the increase in power and torque without it is statistically significant).

 

SteveinFrance

Were those the stats of the bimmerfest forum? If so, that was back in 2009. I also saw that too and also had my doubts on the chip. Since then they have come out with two newer versions of the chip. I have also seen some guy on youtube programming the same chip on his computer so I would have to think its more then just a resistor. The computer recognizes it as a port and then you update the firmware in the little memory that it has.

I do have an OBDII reader with the torque app but I decided on the plug and play version of the chip; so I cant give you a before and after other then what I feel when I floor the gas pedal. I can tell you this - it has been the most significant change I felt compared to the exhaust upgrades and the K & N airfilter. The car runs smoother, responds better and pushes me back in my seat now when I floor it. Sorry I have no statistics to back this up, but most importantly, I am satisfied with the results. On the same note: I have noticed a slight increase in mpg but it wasnt significant on a half a tank of gas so today I will fill up and reset my trip counter. On a half tank I only noticed a slight increase of .5 mpg more but thats was on half a tank of gas without the chip. We'll see at the end of this week.

 

I think that the main thing those plug-and-play generic chips did was to bring the throttle on faster somehow and/or fool the trans into thinking the throttle was pressed further in order to alter shifting. In other words actual power was not changed only the rate at which it was delivered. On the other hand there were also plug-in-chips made specifically for different vehicles that included other things but none of these were as good as hand-held programmers or programs that could be modified via laptop.

Doug

 

This was the thread
Volo flash "Performance Chip" Dyno results are in!: - Bimmerfest - BMW Forums
he says it has the 'upgraded chip' installed.
If you're pleased with it then enough said - I just smelled burning Snake Oil!

 

Chips and programmers are for the gullible. Sorry, don't mean to offend, but the saying "there is a sucker born every minute" fits the bill here. If there weren't, those companies wouldn't still be around...

 

Volo flash "Performance Chip" Dyno results are in!: - Bimmerfest - BMW Forums

Ya. Thats the one I saw dated October 2008. It is not the updated version. Im just simplying stated what I feel has worked for me. Everyone I have given a ride too before and after have also agreed that the car feels faster without me telling them about it until afterwards. Im not trying to convince you guys; just simply stating that I think it works for me. No one on this forums will admit to having tried it or given a review and I felt that it might help someone out there that was considering an item like this.

Like Seismic stated, maybe it changes the rate at which power is delivered. I dont know - but for those of you that have considered this; I do recommend this for now. Of course like anything, maybe that will change in the future. The inside of the circuit board has the specific model it is made for; mine came with 97 Jag XK8 tagged on the inside of a see thru box. Just FYI.. thats all.

 

I've used chips and reprogrammers on a couple of my vehicles in the past and I never felt I got anything for my money. Even placebos have a beneficial affect to some people... Chips and reprogrammers work best on commuter vehicles optimized for efficiency... you'll get a bit more power and lose gas mileage.

On vehicles that are already set up for performance, you're not going to get much of anything. Push the button with the "S" on it and when you step on the throttle make sure you push down hard enough to get the microswitch that drops you down a gear or two.

The XK "S" mode will ramp up your performance and alter your shifting to suit your driving, so you need to drive it hard occasionally for the best benefit. The system needs to learn your driving habits. The XK programming will get very sporty and adapt to your shifting really well. Sometimes it feels like I'm driving a stick shift.