I'm getting a set of Dyno Don's headers. I already have a 3 inch cat back exhaust and stock dual cats.

My engine is basically stock.

I was wondering if it was worth it to upgrade the dual cats. If so, what would you recommend?

(I've tried searching this subject, but haven't had much luck.)

Thanks!
Bill

 

I've seen people say it makes a difference and then others say it's not worth the extra expense.
The factory setup is pretty bad after the cats with how it connects to the I pipe. Catco and Magnaflow(Carsound) offer replacement assemblies but they are not cheap.
Summit -
Magnaflow - MPE-23479 $291.95
Catco - CTO-4153 $340.39

The Catco setup has 2.5" output and the Magnaflow has 2.625" and a better after cat Y.

I personally went with a replacement 3" converter and a pair of 45* bends.

 

I went with the catco dual cat replacments from Summit.

At the time Magnaflow was on back order.

The local shop has used these before.
Fit exactly like the stock ones.

I felt it was a waste of money.
No performance gain @ all.

But then again I already had dual factory cats.

I can't prove it but the dual cats might give some improvement over a single cat.

When my car was mostly stock,
I raced a couple of L98 cars with single fatory cats
and mine was just a little bit quicker.

Not a lot maybe .05 to.1 of a sec.
Just enought to get a win on the 1/4 mile.

I say get rid of them Unless your in a smog state.
I wished I would have.

But you' ll need to cut them out yourself, once the
Shop had seen my car with them on they wouldn't
take them out.
They'd only replace them.