4.8is xpipe installed-weird downshifting now..
 

Installed an x pipe today. Placement is centered where the resonator was. Xpipe is magnaflow 2.25. Assuming exhaust piping is 2.25 as well that was used by the shop. Now in sport mode, the car does not downshift when slowing, it coasts. The tranny seems lost. Didn't have the problem before the xpipe install, but can't think of any reason why the install would cause this either... Anybody had this experience or feedback? Sounds awesome, but performance wise it has me second guessing the install.

Im sure some vet. members will soon chime in to give you some good advice,

But if you feel the tranny is acting funny with shifts, try doing the transmission reset procedure. It might be too easy to be true but its worth a try.

A reset may assist...I suggest a brief road trip (or two :D ), the system should adapt accordingly after a nice drive :driver:

Let me add that randomly, before I installedthe xpipe, the obc reset itself. Wiped out the date and time and reset the gas usage, etc. Today I also got a brief self leveling suspension inactive as well. Hasn't come back on and the height adjustment seems to work fine so far. ??? Thoughts..???

I had no issues after the X-pipe install. It is worth checking the codes to see what has been logged - is it possible one of the o2 sensors was damaged in the process although it is pretty far from the X-pipe.

First, check the voltage of the battery and make sure that its at proper voltage, then check your alternator. you should also look underneath your x to make sure the installer did not burn or tear any wires pertaining to the transmission which sits pretty close to the area he was working by. you can also do the tranny reset which can clear your tranny, just do a search on this to find the proper procedure. good luck

Reset as stated above, and if not, check for crispy computers and wiring underneath.