Highflow cat power

**Chris@Rvengeperformance** · 01-03-2015, 09:53 PM

Who's made power with a highflow cat, such as random technologies or vibrant?

It seems to me if the stock catback is only hurting 16 horse around 600awhp, per ray, that a good high flow main cat with no precats would only hurt 10 or so at that level, maybe not at all around 500.

Any results?

**donniekak** · 01-04-2015, 01:55 AM

I stopped using cats after I blew a couple of them up using anti lag. The first time I launched my car and it just fell on its face. I almost pulled my hair out trying to figure out why it wouldn't make boost. Then I pulled my downpipe and saw that the front honeycomb of the cat had shattered, and was blocking the second part. Also I gained 200-300 rpms of spool without one.

**GTOJOE** · 01-04-2015, 04:10 AM

Noticed mine was louder! does that count? Slight improvement in spool with 13Ts. Had a stock cat went to Maximal high flow unit.

**sergechronos** · 01-04-2015, 08:41 AM

Unless it clogs, I think you're likely seeing single digit HP loses at the upper end from having cats (OEM included.) For the most part sound gets louder more than you'd notice any actual HP increase with a delete vs having cats. Don't think anybody has ever done back to back dynos to quantify data.

**Andr3w** · 01-04-2015, 11:40 AM

I had a race cat with gutted precats on my car. Pulled it out after having my car dyno tuned and the front honeycombs were starting to get deformed and the sides were getting crushed.

Stopped car around 430whp/500tq on e85.

**KeithMac** · 01-04-2015, 11:59 AM

I fitted pre-cats to my GTO for winter use (some reason it smokes excessively in winter).

The difference is night and day, very noticeable around 2500 rpm and peak boost went from 30psi to 22psi.

Soon be summer and I can yank them out again!.

Back to back tests on an Evo showed around 10bhp from normal to Hi Flow main cat though.

**sergechronos** · 01-05-2015, 11:53 AM

Originally Posted by KeithMac

I fitted pre-cats to my GTO for winter use (some reason it smokes excessively in winter).

The difference is night and day, very noticeable around 2500 rpm and peak boost went from 30psi to 22psi.

Soon be summer and I can yank them out again!.

Back to back tests on an Evo showed around 10bhp from normal to Hi Flow main cat though.

If excessively smokey, could be plugging up the cats which would make a very noticeable difference. Are you going from catless back to OEM pre-cats, or from a high flow to OEM pre cats?