The stock cats have to come down to put in the Subframe Connector. One is rattly, and is junk. The pipes are in like new shape though. So: Do

-I buy the replacement dual cat Y-Pipe (Magnaflow has one for $372 all stainless with two cars and new pipes). Any performance over stock?...

-Buy two new cats to replace the two old ones, high temp paint and header wrap the pipes.

-OR do I buy headers and use a replacement Y-pipe and High flow Cat. What is the power difference? Would I even notice it just driving stop light to stoplight?

Thanks! I only ask because I have not had this question before or read anywhere... SEARCHED too.

 

A modern single cat will flow better than the original duals, and is probably cheaper than replacing both.

 

I see, so I don't want to turn the rattly cat into Headers, a Y-Pipe, and a Catback. But, what kind of power improvements could I realistically see with the aforementioned things. I can see being another $900 into this easily with exhaust (Ceramic coated headers, and y pipe, and maybe a stainless cat back. Nothing cheap)

 

The stock dual cat Y-pipe isn't the best design out there. The pipes are restrictive and the Y after the cats is more of a T then a Y. Replacing the cats with aftermarket cats isn't going to fix those problems. But it's still a step up from the stock 3" cat setup. GM claims the dual cats were good for a 13-15% increase in power.

Headers are going to make more power then stock manifolds. Dual cat headers usually eliminate some of the restrictive bends in the stock dual cat Y-pipe. Flowmaster makes a true Y pipe that replaces the tubing downstream of the stock dual cats. Mix the headers with aftermarket cats, and the Flowmaster Y and you're not that far off from the Magnaflow setup. With the headers over manifolds it'd probably make a greater performance improvement.

Headers, with a single 3" aftermarket cat, and mandrel bent Y pipe might make more power then a stock manifold/dual cat setup, but then it should. Likewise headers with mandrel bent pipes, 2 aftermarket cats, and a true Y is going to flow even better.

You can go nuts with ceramic headers, stainless pipes, and expensive cats, and it'll probably make a performance difference, but bang for the buck isn't that great. It'll LOOK great, but it's not going to be a night and day "HOLY COW!!!" difference in the seat of your pants when you hit the GO pedal.

 

After reading the description of the factory dual cat design I am starting to think that mine MIGHT be an aftermarket design.

-Mandrel Bends (factory wasn't mandrel I believe?...), and a clear Y shape. Not a T.

Now the second reason I might think that it has been replaced is the muffler is aluminized, and it has different tips. So maybe someone did a manifold back exhaust replacement at some point?...

So if it truely is a larger aftermarket dual cat setup already I might want to just replace the cats and restore the piping after all. The down pipes have two bolt flanges. That is factory correct?

Also, the only reason I would be shelling out a bit more for ceramic is that they do LOOK better. Not faster by any means lol. I have also blasted the factory coating off of a set of Hedmen's. Major p.i.t.a...

 

Stock dual cat setup



Walker stock style replacement.. Walker Exhaust 16101



Magnaflow 23479

 

I see. I think I will be buying a new y-pipe and headers tonight. I got the dual cats out in a whole assembly, its stock. Anyways, thank you!