I was looking at my exhaust from the cat converter back to the muff .I had this pipe changed about 5 years ago . This pipe looks like a 2.5 pipe ...How can I tell ? Well my tailpipes are 2.5 and they look like the same size . Although , I could be completly wrong .How do they measure these pipes ? Could I measure it with a tape measure on the outside , just wrap it around ...Thanx as always guys ...Wayne
G O D Bless America !

 

I believe its the diamiter.

 

hmmm , but If i measure my tailpipes on the outside with a tape measure , then measure the exhaust pipe with a tape measure .If they equel is it a 2.5 pipe ? ...Wayne

 

More than likely its 2.5". Thats what my old Z28 exhaust was. I doubt that there would be any difference.

 

Yes if you measure both the same way and the numbers are the same... their the same size. I was under the impression they put 2.25 intermidiate pipe on the V6's? I may be wrong but I though thats what they did. I know my 91 RS 305 has I mean had a 2.25. Now it has nothing behind the cat, no muiffler nothing. Then again its not on the road but when it starts look out.

 

Thanx as always guys .I'll have to get that measurement today and give ya'll an update .
Wayne

 

Don't know where I put the tape-measure last time I used it But I looked at the tailpipes and the exhaust pipe real good . Im almost positive that its a 2.5 ...rolled around on my creeper while I was down there and looked at the under part of my car , it looks real good with no rust .I was pretty happy to see it was in good shape .There is a little rust under the bumper on that metal strip .Guess I'll have to try out the new dremol when I get it for Christmas Wayne

 

I'd use a 2in to 3in micrometer. It should read close to 2.5.I've got a diegrinder I love it the 22,000 rpm ,that lovely whine of it makes me happy when I polish motor parts.