X-pipe saga resolved... fuel economy up on hwy too.

[TowX]

Recall I lost power with the installation of my x-pipe and Magnaflow resonators. Had my shop remove that stuff and just install straight pipes and fab a balance tue between them.

Well, after a week of commuting, and towing my car to the track this past weekend I can report that all is back to the way it should be, and I've even gained a bit of power from 3000 up. Plus a nice rumble without any resonance or vibration at all, even pulling my 5000 lb load up extended hills.

So in the end, I have no idea what caused the problem, but still suspect the x-pipe was in the wrong location and the left and right bank pulses were fighting each other. Suppose I could test the theory but I already have way too much $$$ invested at this point to spend any more. I've spent more than half of what it would have cost to just buy a B&B system.

For now, my commuting fuel economy is back up to 13-13.5 from the dismal sub 11 mpg I'd been getting with the other system, and I can again easily tow in 6th gear with the trailer behind at 70-75 mph. In the meantime I will continue to drive my old 528 (closing in on 100K miles) which still gets 20+ mpg commuting with the a/c blowing nice and cold. At least until premium fuel drops back below $4 per gallon.

[TowX]

So I got a chance to get out on the open road without the trailer in tow. At a steady 65-68 with A/C on, averaged 21.5 mpg! At 75 for 30 miles, 19.8. I've never seen better than 18.5 before so something must be working better with this exhaust.

[Weasel]

What it sounds like is that the adaptations needed to adjust to the added flow. It usually takes a few drive cycles for all the adaptive and multiplicative values to re-adjust in the engine computer.