Hey I have an '06 Mustang GT w/ a JLTII intake, SCT tuner w/ 91 octane tune from Evo, pypes offroad x-pipes, JBA mufflers, steeda UDP, and some suspension stuff... After a spirited burnout session (by my father inlaw), the car is different!!

There is a slight loss of power and the exhaust is WAY quieter. It gets quieter as it gets warmer. I sat in trafficyesterday and ithad becomevery muffled. This thing used to be damn loud, now overnight it's not! When I downshift and decelerate, normally it would be loud and gurgly. Now it's quiet. It also "feels" as if when you downshift, that the tranny is not slowing the car down as aggressively. There is definetly something wrong.

I can not figure out what it is and I don't want it to hurt anything. I have so far changed the plugs, cleaned theMAF, changed the diff fluid (i was gonna do that anyways), looked in the muffler (to make sure one of my pissed off neighbors hadn't put anything in it). Please!! Whatcan it be???

Thank you!

 

I have no idea what could have happened as a result of doing a burnout. You've checked a lot of things but at this point you should try reloading the tune. Can't see why anything would have changed but it shouldn't hurt to reload and see if your performance comes back.

 

I've reloaded the tune---it's the same... Gets quiet and lower loss when it's warm...

 

My car is loud on initial start up and gets quiter after it warms up(but no to quiet) its just a normal thing when the car warms up it runs smoother.I think its all in your head.

 

I thought that maybe it was at first, but there is definetly something wrong... I'm talking about going from LOUD, to sounding like a stock Honda Accord overnight! and there is definetly power loss...

 

Didone of your catalytic converters break apart? That would cause a car to get quieter and lose power.

Just thinking out loud....

 

good thought; i would check that..........

 

O/R x-pipes. I have no cats! Man I just drove it again and it's freakin weird. It is so quiet when driving.

 

i have no ideas to share. i would contact a respected company or stop by your local mechanic and let him have a look

 

Sounds lke a compression prob. pull one plug at a time check the compression of each cylinder. Maybe a few burnt valves, busted rings, like that...