Searching isnt helping. I am looking to get a highflow cat. I have heard of all the boost spiking/creeping that happens with the stock twins when you remove that cat completely and put a mp.

With that said I was wondering if anyone knew the best flowing cat out their. I was looking at the petite one but its $$. Is their one that is proven to have the highest flow?

Hopefully someone has some experiance with this.

 

seems to me a higher flowing cat will still give boost creep. Flow is flow, right?

 

high flow cat still gives you back pressure a mp doesnt. Thats waht creates creep. At least thats what I thought.

 

I am also interested in the answer to Dragon's question.

 

I didnt notice any boost spike/creep when I switched to a highflow cat (Ntech). I also didnt notice any change in performance. "Highflow" is just a name... dont read into it too much.

 

I was under the impression that taking out the main cat and add a MP you notice huge hp gains. The problem is that the stock wastegate cant handle the extra air flow. The outcome is boost spike or creep.

Now with a high flow you get more airflow its restrictive but not nearly as restrictive as the stock one. (Basically a mp with back pressure)

I have heard that a high flow cat gives more hp. Alot of people who have them end up going to a mp anyway thats actually why I posted this question.

I am looking to stay safe. I also dont want to get a mp an buy the added fuel upgrades and tuning if I have to take it all out.

 

downpipe is between turbo and catalytic converter and mid pipe is between catalytic converter and muffler. am i correct on those? what's a cat back then?

 

cat back (CB) = muffler
We call them cat backs now, because "muffler" is a misnomer.

The downpipe goes between turbos and main cat (cat = catylitic converter). It replaces the restrictive and easily clogged pre-cat.

A midpipe replaces the main cat.

 

so midpipe = main cat? what's with all these names for the same part?

 

mid pipe is basically a straight pipe which means theres no catalytic converter.


the cat is there to help pass emissions but kills your power like crazy.


the catback or exhaust is after the main cat.


people refer to it as main cat in the US because we have precats also. the precat is located before the main cat and the straight pipe replacement is known as the downpipe.

 

I have a Bonez high flow, supposed to be one of the best out there. I purchased it from rotary performance (rx7.com). So far I completely love it. Its not really loud, no nasty gas fumes, and I have definately noticed a performance gain over the stock one.

Supposedly a midpipe will give you a larger gain in the upper RPM range, due to the fact that there is no resistance, and there is a higher volume of exhaust gas at higher RPMs. This thereby increases your peak horsepower.

The largest area of performance gain by adding a high flow is more in the low and middle range of the RPM. So basically, using a high flow will give you better low end power than using a mid-pipe, but a mid-pipe will give a lot more power up top.

Someone posted some dyno results that prove this theory a while ago. I'll see if I can dig those up for ya.

Rob

 

I can comment on three High flow systems
Pettit CAT
Random Tech
Bonez
We have had all three.
The Pettit CAT plates broke off and failed within 6 months. Replaced it with a pettit and it happened again.
Random Tech CAT clogged in one year.
The Bonez CAT has been on for 2 years now and no problem.
My buddy, Wael, dynoed his car with Bonez and midpipe.
Midpipe: about 30 more HP on top end compared to High flow CAT. BUT the CAT had provided more low end, mid HP and torque OVER the midpipe. CAT provides better street/everyday driving since more power is available. Midpipe Needed for Max HP.
CAT greatly decreases the ehaust noise.
I hope that helps.

 

http://www.efini.net/hpcomparo.htm
when I saw that in my Rx-7 research, I was determined to get a Hi-flow. I bought someone's used ATR cat, thinking it would do a lot. Turns out the only difference that I can honestly notice is the rotten egg smell from not hooking up the air pump and louder exhaust. Add that to the joys of 16 psi boost spikes @4500 and $450 in boost controllers. My friends say that the car is at the point where anything under 30 hp or so they won't notice, so I'm pretty disappointed. I'm planning on visiting the dyno again sometime soon....
(to be ocntinued)
-jerry

btw, I only paid $230 shipped compared to a new bonez @$500+)

 

r0t0r-rooter - That is exactly the dyno plot I was talking about. Thanks for finding that, saves me the work of doing it.

Thats exactly why I like my high flow instead of using a midpipe. I'd rather have a little more power on the lower end. Much better for street driving in my opinion. Plus I'd rather not have to deal with boost creep and all that

aimedhigh - I obviously don't have the high flow experience that you've had, as I have only had a Bonez high flow on my FD. But you're not the first one I've heard saying similar things about pettit's HF. Thats kinda why I shyed away from them and went the Bonez route. It may be a little more expensive, but I felt that it was worth it.

 

I second the Bonez High-Flow CAT as a very good CAT. I like the inner construction as it is made from ceramic blocks that apparently are more effective at disipating heat I did notice a performance improvement especially at the lower end RPM's, which has already been mentioned. Worth every penny IMHO.

 

Another thumbs up for the Bonez...

 

ok.. Jason (JT-imports) help me out, is that RE amemiya 'converter' you offer a kind of high-flow cat?? it looks nice whatever it is.

 

Saxyman990, Curious what you think about our dyno results pre (red lines) and post MP & DP (blue lines). There is bacically no improvement in hp until after the second tubo kicks in. Great for the strip and track time in the upper rpm range though.
https://www.rx7club.com/forum/attach...postid=1181103

 

Nice feedback "AimedHigh"! I would have expected the opposite results. Oh, no one has mentioned the Tri-Point Cat'?

If these all suck, we need some feedback on the JDM versions. For about $650 shipped to your door their is Border Racing and RE Amemiya's high flow cat's from jt-imports.

 

i'll put a thumbs up for the n-tech hi-flow. I had it, supposedly flows 96% of a midpipe. Car got noticeably louder and power increase was felt all across the board. FYI i also hookedup the airpump.

Danny

 

With the high flow was 330 and with a mp you gain an extra 34 hp. Damn thats alot of hp. How much hp are you actually gaining with a high flow. 5-10 hp for 500 bucks seems a little high, no?

 

For me I wanted a mp for high end hp.

 

I bought the N-tech hiflow cat. I also felt good, noticable increase in hp and responsivness as well.

 

Goodfellas is selling one:
http://www.thepartstrader.com/Single...=101&C2ID=1004

That's a good deal. I paid 374.00

 

I am thinking REAL hard about getting that N-tech, but since I am going to use the airpump, I am curious about the "with some modification" blurb about hooking up the airpump in the ad.......
Are we talking major fab work, or what?