So I went to Parkway Honda to ask them if they knew any differences between the OEM SiR Muffler and the OEM Muffler for my Si, The parts guy went to ask the mechanic and all they told me was there is two different parts listing but they don't think theres any significant difference.

That's why I turned to you guys, hopefully you can help me out.

So what is the difference between the two. I'm just a bit confused as there are two different listings. Is there a difference in sound?

Thanks in advance guys.

 

I had a full SIR OEM Catback (Midpipe and muffler) on my old 98Si. It was slightly bigger in diameter (maybe 0.25") and it did sound a bit louder. Side by side with a regular Si exhaust, you can see the slight differences in shape and size.