What are you talking about... I've daily driven with my N-tech hi flow cat for 1.5 years at 14 psi and notice no difference from the day I put it on.

u might be a lucky one.

I know 2 guys that have been through 2 of them in 6 months running 390rwhp.

Maybe it's the CA gas.

Ditto, I know HF cats are not as high quality as the stock unit and can't take as much abuse but they aren't total crap. I'm expecting about 5 years from mine. Cut that in half if you have no air pump.

As for my old stock unit it was not at all clogged. I think the fact that the HF cat only produced higher numbers above a certain RPM and was EXACTLY the same under that RPM proves that point. If my stock unit was clogged I would expect better numbers across the board.
dis1

I have been running mine for well over 6 months, close to a year. I know several guys running HF cats that have been doing so for much longer and that run their cars much harder. They have reported no problems. Perhaps your friends in CA don't have functioning air pumps or are in need of a tune.

ummm whats this loss of low end torque with a midpipe crap? is it true.I talked to a few other people and they said that their cars spool up quicker with a midpipe.Wouldnt this translate to quicker throttle response and much earlier delivery of torque thanx to the faster spool up?

I noticed low-end TQ loss, but it's made up in the top end.

Has more of a single turbo feel.

The dyno plots I have seen comparing midpipes showed loss at the low end and gains at the high end. The gains at the high end are what make it so attractive as they can be substantial.

Basically the rotary needs some back pressure at lower RPM to function optimally.

I put the Bonez Hi-Flow cat in, and im very dissapointed.. No gain at all on the butt dyno, and it did not wake up my exhaust at all. Not Impressed!~!

Which dyno plots? Better not be Wael's, where he had massive ignition failure in the mid rpm range of a mid-pipe run, posted on his web site. Mid pipes don't make step changes in torque dyno runs, as his showed.

Sorry but I don't remember.
dis1

People need to post more facts instead of I heard this or I know someone comments.
Fact #1: The high flow cat will not give "significant" power increase at the SAME boost level, my dyno test showed only 6 hp difference and it could vary +-5 hp easily from run to run.
Fact #2: The high flow will allow you to run more boost if you have a boost controller. I tried to run 15psi with the stock cat, the boost capped out at 12. By allowing for higher boost the hi flow will help in producing "significant" power increases.
Fact #3: The high flow runs much cooler than the stock cat (by as much as 300 deg F). I measure it with an IR gun.
Fact #4: The exhaust tone is different, better or not depends on the combination you run (High flow and cat back).

When I had a main cat with 200k+ miles on it I still managed to boost creep to 17psi before grenading my engine.

What about nifty Knightsport metalic high flow cats, anybody ever test them?

cost plus emisson concerns will the cat still be strong 2- years later?