U just have a heavy foot. I've seen how u drive. U only get 9mpg with that heavy foot

See post 24 in this thread http://www.xoutpost.com/bmw-sav-foru...ght-pipes.html

By installing straight pipes and removing your resonator (basically a mufflered x-pipe), you've removed the scaveging affect of your exhaust system. Your butt dyno may tell you it's faster because you hear more sound, but I'm almost positive you're down on power now and will be fouling plugs sooner than before.

:iagree:The resonator internally has an x-pipe, so removing that x-pipe took away it's scaveging affect on the exhaust.

hahahaahah Its hard you have to hear how it sounds now.

What!!!!:fired:

That is some interesting info. When I bought mine, the stock resonator had been replaced with 2 bullet-style resonators. Would I benefit from swapping to an x-pipe currently?

Based on my understand of how an x-pipe works, I would presume so. I know lots of 740 guys who have either went w/ a plain x-pipe or one of Magnaflow's internally x-piped mufflers, which is basically a duplicate of the stock resonator. To be honest, I think the stock resonator is more of an h-pipe design, but either way it still serves a balancing/scavenging purpose. Someone can find varying differences all day long about exhaust diameters, if backpressure affects computer controlled cars, etc. I just know coming from all FI cars before my BMW's that I'm not going any bigger or completely deleting what more educated engineers designed into my exhaust. The F350's I had in the past, its proven to open up the exhaust because it helps the turbo spool, opening the exhaust and/or deleting the scaveging affect on a non-FI car would just ruin the bottom end...like it did in my 7. Just my .02.

M5J- By deleting it do you mean going to straight pipes? I was looking to add a x-pipe that still does have a scaveging affect right? I dont wanna ruin my engine. Thanks

Removing the resonator for an x-pipe is absolutely fine, I just personally wouldn't delete the res for straight pipes because I know the benefits of an x-pipe. Even the 540, which only has a single exit exhaust, still has an x-pipe immediately after the cats.I wouldn't say it'll "ruin" your engine, I'd just think that since all the exhaust isn't exiting the intake anymore that it would cause premature fouling to the plugs and the poorer gas mileage he's experiencing.

you would or would'nt

sorry reason i ask is, i have a cousin in germany and long story short got me the hartge x-pipe :) ill be making a post soon. thanks