Hey, I'm driving a 1995 z28, and I wanted to throw a new muffler and exhaust tips on it. I was wondering if anyone know the stock in and out tubing size for the muffler? Thanks in advance.

 

I believe that it's 2.5" in and 2.25" out.

 

Alright cool, thanks, and although I'm pretty sure, its offset in, and dual out, correct?

 

Nope its 2.75in stock diameter read here there is a sticky at the top of the forum...https://www.camaroz28.com/forums/sho...d.php?t=371087

 

Alright, so its 2.75 both in and out? Because I also just called Flowmaster and they said it was 2.5 both in and out, and then Slimjim gave me different numbers too...I'm so confused to as what the real size is haha

 

I just went out to the garage and measured the old/OEM stock muffler from my 94 Formula. Inside diameter of the single inlet was 2.50". Outside diameter of the two outlet pipes was 2.25".

 

OEM specs were for a 2.75 OD intermediate pipe and 2.5 OD outlet pipe(s).

 

Although, quiet and boring I replaced my exhaust keeping the stock setup. Original intermediate pipe is 2.75 inches but reduces to 2.5 inches entering into the muffler. Tail pipes exiting the muffler are 2.25 inches and so are the original spout style tips. I used Walker muffler #18375, right tailpipe #42541, left tailpipe # 42533. The left tailpipe has the hanger welded to it also. I used the factory spouts to keep the original look and it fits together good and only costs around $100.

 

Hm. So yet another different answer. Might have to call up Chevy and see what they say....

 

I just went out and measured the exhaust parts and this is what I have:

Y-pipe - just under 2.25" OD (more like 2 3/16")
Inlet to converter - 3" OD
Outlet from converter - 2.75" OD
Intermediate pipe - 2.75" OD
Inlet to muffler - 2.5"
Tailpipes - 2.25" OD

 

Three people have actually measured it for you and told you what it is.

 

The inlet on the stock muffler is 2.5" and the outlets are 2.25" and it's a crossflow design (meaning there is an inlet and outlet on one side and an outlet on the other side). The intermediate pipe coming into the muffer is actually 2.75” and necks down right at the muffler inlet to fit the muffler’s 2.5” inlet.

What I usually do is get a muffler with a 3” inlet and cut the intermediate pipe right before where it necks down and weld a 3”, 3bolt collector flange to the pipe and the muffler. The other possibility is to use a 3” OD, 16ga bushing over the 2.75” pipe pushed into the 3” muffler inlet and clamped or welded, the reason that works is because exhaust pipes are measured OD and mufflers have inlets with matching ID’s