use the factory aqua header,,not the duece one... the only length that will work well is stock length,,, header against pipe,or a hair away... that pipe does not perform well on the aqua,, it robbs gobbs of torque from it which in my mind makes the aqua shine over the st engine... that pipe will want to pull way more rpm than the aqua pipe,,,and less prop in the process... the center band of the pipe is too long for the aqua.... if you take and cut the q pipe apart,,,remove 1/4" from the center band and put the pipe back together with out the muffler it will wake right up,,,supporting the torque the aqua puts out,,, with much more rpm.... the testing ive done with that pipe has the header shortened 3/16" also...
im not sure if you are looking for quiet, or more power,,, but what you will find is quiet...
ive had my hands in tons of aquas,,, ive seen only three pipes work well on the aqua,,,well now 4 but that q pipe i modified you cant buy so it dont count..
the stock pipe (shortened 3/16")
macs 1110 pipe (shortened 1" in the header section,,, puts you right around 8 1/4",,, shorter works but starts to be peaky at less than 8" at my elevation anyway)
an un-identified macs pipe (i think) i have (was told it was a 1110 but its not.. this pipe works very well,, but with manufacturer and number unknown its useless to you or anyone)
then last was the modified q pipe...( 1/4 off center band, and no muffler,, 3/16" pulled from header length....
hope this helps...
alden
