Im new to Honda,but I love the 94 SI I bought,it reminds me of my DADS 65 COOPER S .Any way Ive noticed that my cars exhaust is 2,25 or 2.5 in. all the way from front to back exept the last pipe with the muffler and its 1.5 at the most this seems wrong,Im not too concerned with noise so should I open it up with an equal sized free flow muffler or is there some benifit to the step down and increased back pressure? Im thinking of turbo charging it down the road,Im a Saab owner also{SAAB 9-3, STGE. 3,260H>P>} THANKS DAVE S>

 

1.5" exhaust is the stock size IIRC. the rest must be aftermarket stuff. 2" is about as big as you would want before you add forced induction.

I doubt you'll see any gain or improvement from increasing the muffler tube diameter prior to adding a turbo. you may like the sound better... it's up to you.