I bought a magnaflow catback system. It had a 2 bolt flange where it bolted to the cat converter. So thats all good and fine, but my cat had a 4 bolt flange. Im just wondering if the 4 bolt flange is stock, or some aftermarket thing. And also my friend gave me some Dynomax headers that came of a car exactly the same year as mine, and my Y pipe is too long where it connects to the headers, and the flange has the wrong fitting. Im going to do some fab work on the Y pipe to make it work but as of right now im wondering if this Y pipe is stock, or stock of off something else. The Y pipe is also very heavy and thick. I'd be great to have some help here, ive searched the exhaust forms and cant find anything about it. Im going to make it work one way or another. and i guess the cat doesnt really matter because im going to do a cat delete and bypass it. Thanks for the help and input.

P.S. oh and also when i bought the car it had a transplant 355 in it. nothing special.

 

There are two different styles of exhaust for an 84 thirdgen. The smaller LG4 style, and the larger L69 style. I'm guessing you have one of each and that's why its not bolting together.

 

Here's the LG4 and the L69 Y (note the four-bolt flange):

https://www.thirdgen.org/forums/atta...tion-ypipe.jpg

FYI: The L69 cat had the four-bolt flange on both ends.

JamesC

 

So it looks like i have the L69 Y pipe. It looks just like mine. Almost oval. Thanks both of you. it helped.