Hey guys,

I just got finished installing my new headers and I have one problem. It seems that the new 3" y-pipe is actually smaller than my original stock y-pipe...The original stock y-pipe measures approximately 4" going into the cat. I didn't think it was that big. Can anyone confirm this for me?

I haven't measured it yet coming out of the cat (ran out of time). I had thought that the original pipe would be 2.5" or so, which is why I went with the 3"...I'm a little confused. The front side of my cat is larger than my y-pipe so I'm going to have to make the exhaust larger going into the cat. Is this normal? I always thought you would reduce going into the cat. Could it be that the cat is smaller on the back side?

If...my original y-pipe is indeed larger than my new one, how much of a performance hit would I take going from a 3" y-pipe into a larger...possibly 4" catback? I'm going to be out of town for the rest of the weekend, but on Monday I'm going to actually measure the pipe from the cat out the back to see what size I'm running. Maybe some one in the past swapped out the original system for one that is a little larger?

So...I'm confused. Any thoughts on this?

 

You have the L69 wide mouth cat....the I pipe is 2 3/4 ".......you can have an exhaust shop expand the oval pipe going into your cat so you can install the y pipe you have now.Talk to r0nin89 I sold him my L69 cat (I kept the guts) and he had it attached to a 3" y pipe
Good luck,
Mike

 

Technical error.

 

Another.

 

The Hooker Y is round; the stock L69 is oval with a 4-bolt flange (below). The direct fit cat for the Hooker Y is Catco 9118.

https://www.thirdgen.org/forums/atta...please-cat.jpg

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

JamesC

 

Thanks for the info. I have the L69 car...at least per the vin number, engine and options on the car. However I do have the oval 4 bolt cat. What the shop is going to do is cut off the 4-bolt flange from the old Y-pipe, spread it out to fit the round hooker y-pipe and then weld them together and bolt it up. It should work ok until I can put a new catback on it. or at least a new cat.

I guess I'm not too worried, because even though it's a little ghetto, the engine will still flow better with the headers than it did with the original exhaust manifold. I was just a bit confused as to why the original pipe is bigger than the new one. From what you all are saying, it's not bigger, just a little different shape and so it "looks" bigger.

 

I'm unsure of how much the shop will charge you for the modification.
The correct cat for the Hooker is around $120 from Jeg's/Summit--can't recall where I purchased mine offhand.

JamesC

 

I'm looking at $275 for the header install complete. This includes modding it to fit the cat.

 

Yeah 10mins of MIG welding and all of the sudden an oval pipe fits onto that Y. My cousin did it for my and I was pretty convinced we would need to fab up a roud elbow but nope manages to weld it right up and plug the over hang with the weld. Runs great and now noone is gonna take my cat off to see if its gutted...