what is the pipe on the ap2 exhaust?
 

there is a pipe that is welded in at 90 degrees after the cat but before the split
what is it for?

It's a hemholtz resonator, used for tuning out unpleasant "droning" from the exhaust.

after many miles on the freeway with my ap2 i need to call Honda and let them know it didn't work. :p

Get an Invidia or a single exhaust without one and you'll appreciate it being there :D

my ap1 has the same piece

mine too. A 2001. I was wondering what it was earlier this week when I was installing my test pipe.

All stock S2k exhausts have it.

My Triflow exhaust has one but its at 45 degrees

Or maybe it does! :o

Drive Safe,
Steve R.

can one.. theoretically sawzall it off.. and weld it onto an aftermarket muffler? i assume 1 can.. but i also assume the resonator is frequency dependent and tuned to the stock exhaust, hence inaffective for aftermarket units...