currently have a 89 formula 350 w/only 7k miles on it. i also have at my disposal a brand new 3" cat-back flowmaster exhaust system that i am debating whether to use or not. is there a noticeable difference between stock (2 1/2"??) and 3" or should i just replace the muffler. future mods are slp intake runners, chip , headers and cai

 

if its free its for me.
thatz the way i ooks at certain things. if it better than what you have replace it,
so in your case i would put the cat back on. and it would also go good with the headers and a high flow cat.

 

Replace it if you have it, i mean why not?

 

You'll definately feel the pick up in HP on it, specially once you put headers on, if possible it may be easier to do it all at once.

 

7K miles?


Leave it stock and take it to shows

 

I agree. The car isn't even in double digits.

 

I've read on here quite a few times that the stock pipe on the TPI was 2.75". Is that right?

If so, leave it alone. At least that's my 2¢

100% stock is something anyone can rarely say these days. Someday it might be a good thing.

 

Mine is all stock with 86k on the odometer . that stockness is gonna be loss soon im gettin my catback within the next month (finally)!