So quick question as I tried to look for answers in the forums and maybe I didn't look hard enough.

Stock 2012 xkr with 44k miles on it. Just had a fresh 45k service done.

I installed bmc air filters and viezu custom tune, car put out 490. Put the viezu upper pulley on and car put out 535. So do I need the extra power beyond that...no, not at all but from stock to adding these things, I have talked to viezu and they state that the xkr should be putting out 550 and above from all their experience.

So from a pure conversation standpoint and your experience, should I let this go or should there be things/places I should check in the car that would be robbing back the power, from a stock standpoint prior to doing these mods?

Appreciate the help.

 

How are you getting these numbers? What were they before the tune install? Also numbers are only a reference, not necessarily accurate plus there are numerous variables that have an impact. Best way know what gains are to be had is on a 1/4 mile track, how many seconds or fractions are saved after each change.

 

Apparently the x-pipe is important for getting the best out of the tune, could be losing out there. As a bonus you'll get a better sound to!

 

Not sure why my reply didn't post but the numbers are from dyno tunes yesterday. Unfortunately didn't do any numbers pre tune.

In regards to the X pipe, without going through a bunch of posts, what x pipe is recommended or configuration?

 

Your car is supposed to have 510 BHP. The only number you posted that matters is the 45HP gain from the pulley. Assuming a 15-20% loss at the wheels you have at least 560+ BHP but without a before baseline you will never 100% what your gain was.

 

Then your post-tune numbers don't really mean much on their own...

Who's dyno? Were was this hp at the wheels? Calculated at the flywheel? Plucked out of the air? Is there a printout of the results?

This one



It's the factory Performance Active Exhaust, used on the XKR-S, and optioned on some XKR's.

 

If you do the math - 535x1.15 your BHP is about 615. I'd say you are where you ought to be.