ThunderBolt Cats, Stock Manifolds???

[ConElite]

I can get a pair of Thunderbolt High-flow Cats Real cheap, but I dont know if It will be possible to add these with my stock manifolds and Simply get a custom y-pipe.

They are 3" in and out. I think the stock pipe is like 2"-2.5". Will it be possible to get it to all work together without relocating the cats and My guess is using the Flanges from the original Cats?

[FTA1995]

You can just get reducer couplings on both sides, 2" to 3".
Or just find a way to weld the ends closed a bit, wont look pretty, but it will work.

[Injuneer]

Sloppy transitions - either sudden enlargements or sudden contractions in pipe size - will hurt exhaust gas flow. You want the longest, smoothest transition you can find.

[ConElite]

Sloppy transitions - either sudden enlargements or sudden contractions in pipe size - will hurt exhaust gas flow. You want the longest, smoothest transition you can find.

The only sloppy part would be the transition From the Flanges that bolt to the Stock manifolds which would only be like 4" or less form the Flange to thecat, Then from there its the cats, 3" custom Y-pipe and My Cat-back is already 3" all the way back. Should be alright no Fred?

[FTA1995]

I guess you could reform the openings just a tad to smooth that transition out. Least turbulence better the flow. It will work but as far as ill effects on engine output? negligible at worst but still 6 or 7 HP is still 6 or 7 HP.

[FroSSty]

Two Questions...
Doesn't Cali do a visual inspect as well as smog?
Do you need new cats?

[ConElite]

Two Questions...
Doesn't Cali do a visual inspect as well as smog?
Do you need new cats?

Yes, But the thing im trying to do is not relocate them, which should make it street legal.

Plus, where I go the guy never bothers looking under the car, just for headers.