Ah .. actually mine is different ... it's a 2.5" downpipe going into the flex joint after which it's 3" right away .. going to a flange going to the 3" midpipe.

http://vibrantperformance.com/catalo...80ce7d90cb3f52

I'm going to go for this one ... i can weld this 18" resonator in there.

3" x 18" by 4"thick.

b.