What does where you live have to do with this discussion?

 

This is laughable....some of that may be true for a naturally aspirated engine, but not for forced induction.

 

Laugh I dont mind, but dont forget to thank me when I actually help you gain power. You are the guy that removed the resonators from an intake to gain power. I showed you how that REDUCES power. Only because you still had the original intake. Otherwise I would not have rained on your parade. Same with this gentleman, he has a choice to go with the 2.25 or 2.5. As others pointed out its the choice the XKRS made.

Here is a brilliant article that explains what I said. Including forced induction!! Exhaust Pipes: Is Bigger Better? | outbackjoe

 

Depends if you are doing a live dyno tune. If they are just loading a tune file, then it won't matter, but if a live tune on a dyno I would think the performance difference between the 2 exhaust systems would come into play.

 

look I really understand that some folks want to change something just to be unique, no matter what. I get that and respect it.

As a Jaguar engineering fanatic, I merely point out the scientific counter-argument, for the other conservatives who maybe questioning if Jaguar indeed did the right thing.

 

I've read the article and it makes perfect sense. I feel a reduction of power at low RPM's, but it does seem faster when I'm gunning it a little. I'll have the 2.5 pipes removed on Tuesday and re-install the 2.25 in pipes. Thanks.

 

I'm going to ETG. I'm pretty sure they're just going to do a tune file and upgrade the pulley. I'll tell them what I did and see what they say. I really, really wish I had checked in with you guys first. Thanks.

 

I appreciate your candor and giving science a change.
Just know that Jaguar engineers do have some education, at the very least they do know how to give you the best of all worlds. You can do better but only by giving something else up.

The resonators on the intake for example- look at their decision process. They gave you a well tuned intake pipe that gives you more power than any other type of pipe you can have- guaranteed! But a tuned intake means lower intake sound, so for those who still want the superficiality of sound they did that whole fake sound thingy.

 

You haven't shown me anything (for my exact application), I'm attempting to show myself by doing something. If it is detrimental to performance, then it will go back to the stock intake. And as far as the exhaust goes, hell, if velocity is what we need let's all change our exhausts to 1.5"...that ought to give us a lot more velocity!

 

No bro, first of all I am on your side and just helping. You cant just have velocity, you need volume (CFM) too. Its a very careful dance between the two. You have to get perfect balance to NOT lose performance.

Here is the GREAT NEWS this extremely complex calculation, which diyers and small shops cant do- has been done for us. I dont think many people realize how much R&D is done at multi-million dollar facilities to derive the correct balance. And even then there are compromises.

Here is the thing to get your arms around- an engine is basically an air pump, the volume of the pump (displacement) is what both ends have to be carefully matched to. Where it becomes rocket science is the pump and air change characteristics on the bottom-end vs top-end. If you change the volume or velocity on one end, you negatively affect the other.

If you want performance gains you have to go in the other direction, put larger/better resonators on the intake, not take them away.

 

Hi forum,
sorry for the delay in chiming in. as fate would have it, I get my Jag tuned then get slammed at work and can't enjoy it. Anyway, met with Jags from ETG. Very knowledgeable guy and passionate about tuning with I appreciate. I was in and out in about 2 hours. While driving up to LA, I noticed my car starting to shake and I knew it had to be a motor mount. I was going to let the shop where Jags did my tune replace it for me, but it was getting late in the day so I nursed it back home. Missed my app't at the dealers to get it replaced, work, work, work, so I'm looking at next Wednesday before that's repaired. Then I'll go to my favorite patch of road and give her a try. Then off to the track!!....Eventhough I'm babying her, I believe I do feel a difference....could be wishful thinking though.