[SV_Mustangs]

I Bought a MAC Catback Exhaust 2.5" pipes with 3.0" STAINLESS STEEL tips for 1999-04 with stock Y pipe.

I was wondering since i am going y-pipe, if it made a difference if a custom 2.5" Y pipe was made if there would be any change in power Positive or negative?
Or any other custom changes Besides H or X that would create a positive change?

[heavy metal]

The diiference between the stock y and a larger one will be the backpressure.The stock y will do better on low end power where the larger one will do better on mid and top end.

[poultry411]

Originally Posted by heavy metal

The diiference between the stock y and a larger one will be the backpressure.The stock y will do better on low end power where the larger one will do better on mid and top end.

spot-on. FYI, you're cats may inhibit the amount of gain w/ a larger y-pipe. High flow cats also might cause too much loss in back pressure also, but on the other hand you are remaining a single pipe system... Hmm, food for thought. I'd refer to a well known professional personally.