Just did X-pipe and Magnaflows like Steed77, lost power!
 

Just had my exhaust fab guy do the same thing that Steed77 did, same Magnaflow resonators, and x-pipe. Hooked up my trailer to haul a short distance to the track yesterday and I'm way down on low end and midrange torque. Pulls reasonably well up top but where I used to easily pull in 6th, now I have to pull in 5th. Felt OK without the trailer, but good heavens, does it now fall on it's face with the load of a trailer back there.

So it's back to the shop this week to go back to stock. Total waste of $500. Only thing I can think of is Steed77 has a 4.8 and mine's a 4.4 though that shouldn't make a difference. Doubt it's the resonators, more likely the x-pipe. My guess is it's not in the right place. There's a science to where to place an X or crossover.

Not trying to knock what Steed has done, but just didn't work for me.

WOW sorry to hear that. Are you positive you are loosing power? Air temps same as before? same gas?

I have definatly picked up some. Do you have an intake?

I wish I had the time to Dyno before and after. I'll bet I got 10-15 real HP.

Absolutely down on power. Same tank of fuel, air temp within 5 degrees.

I'm quite familiar with how the X pulls my trailer and unless I have a serious headwind, I can pull at 70 in 6th on flat roads. Yesterday I could barely pull the trailer in 6th at all, and even 5th was taking more throttle just to maintain speed on flat ground.

Going to get under the car this afternoon and see if I can find anything obvious. The only thing I did notice when looking over my invoice is that my shop ordered Magnaflow 2-1/4" mufflers and x-pipe, not 2-1/2". But I need to measure the stock pipes going into the x, and see what size it is. But the x-pipe is welded over the top of the inlet pipes so it doesn't seen as if the size could be the problem. Just continues to baffle me.

Strange. OK good on the fuel and gas. Hummm, The 2 1/4 maggies may do it, that would restrict flow. My 2 1/2 X was puffed to go over the OEM pipes. :dunno:

I also do not tow, so maybe I did loose some down low, but it sure does not feel like it. The mid and top-end sings for sure.

Steed if it was that easy to gain 10HP why wouldn't BMW do it from the start?

That's because not every BMW owner likes the loud growl of an X-pipe over a quiet resonator.

This has been the day for vehicle problems. Dedicated the day to work on the 911 for the next track event. Had a pretty noticable bang in the right front at Mid-Ohio a week ago and felt it in the steering wheel too. was the end of 3 days so I just went in and loaded it up on the trailer. So tore into the front end trying to find the source of the noise. All the suspension parts are fine, so went to change the track pads and bleed the brakes. Found my noise- broken front rotor! Cracked right through three of the drilled holes. 10 days of use and now just boat anchors.

Got discouraged so took a break and got under the X5 to measure the pipe diameters. Not sure about your 4.8, but my 4.4 pipe size is 55 mm which is slightly under 2-1/4" OD. So the Magnaflows should be OK. But it looks like the way my fab guy attached the x-pipe, he inserted the inlet of the x-pipe INTO the head pipe which would be a serious restriction. Guess he and I will have a conversation about it tomorrow. I'll keep you posted.

Not only that, BMW has to stay within its market guidlines for competitive purposes like all of the other manufacturers.. This keeps things coming form the factory under controll..

YOu don't think they don;t know how to make a faster car?? They do, all of them do.. They just can't. Everything has to go in increments so that one won't get too far ahead of the other.. Think back 10 years ago when 215HP was the magic number...

maybe have them take the resonators off.. and just stick with the xpipe.

Actually thinking about just the opposite- loose the X-pipe and leave the resonators. I think the X-pipe may be the culprit, and it's pretty easy to check by yanking it out for now. But I don't want to permanently loose the effect of a crossover. Even the factory center boat anchor of a muffler was a crossover of sorts to smoooth out the exhaust pulses.