Does anyone have any dyno sheets with ref to horsepower increase from stock main cat to a hiflow cat.
I am looking for the best flowing cat where I can keep my airpump too. I think the stock main cat must flow pretty good as most people to get any significant power increase tend to replace with a midpipe instead, which I don't want even the resonated midpipes are too loud, and they don't utilise airpump from what i'm aware of. I am looking for lowdown torque rather than top end power.
Any suggestions anyone please ???

Rgds

Brian

 

I liked my n-tech one that I had a while ago. Now its no cat so.....

 

was there much power difference, and did it last. Thats another thing I forgot to mention in previous post apparently the pettit one works ok for about 6 months to a year and then is all clogged.

rgds

Brian

 

save yourself some money and get your power by going with a MP!

 

Power increase was there, don't know how much though. It lasted about 5k miles and then I sold it and I suspect it is still in good working order. I think the n-tech are supposed to flow the best of all the aftermarket cats.

 

There are many reasons not to go with a mp but if you can I would agree. If you need the emissions, don't want to smell like fuel all the time, hate the noise too much (although hi-flow cats are still loud), etc. then go for a cat.

 

Don't waste your money on an N-Tech cat. I had one and we measured 7 LB of back pressure with it on. Replaced it with a MP with a Borla race muffler in it and the back pressure dropped to 2 lb. Unless a manufacturer (N-Tech does not make their own cats) can show you back pressure numbers or dyno plots that show a HP increase I would be very skeptical of their claims for their products.

 

probelm is if I get a midpipe I have to loose my airpump is that right ??? and is there such a thing as a normal sounding resonated midpipe a sthe only ones I have heard are extremely loud.
by the way what is standard back pressure with main cat on. It would be interesting to know if the aftermarket ones are actually any better than stock.
rgds

Brian

 

I've got a downpipe, Bonez hi flow, and a Blitz Nur Spec cat back. My exhaust is just as loud and almost as smelly as my friends with the exact same setup but with a mid pipe... The hi flow cat is 3 or 4 years old, dunno if that makes a diff or not.

Cavell

 

Hi Brian,
I have removed my cat but retained my air pump, this is due the air injection which occurs prior to the cat, from the air I believe injected into the exhaust port area. I believe this to be correct but wouldn't gamble large amounts of cash on it.
Rgds
Chris P

 

Hello mate! are you chris p on fduk ??

 

Brian,

Any time that you free up some backpressure you'll lose a little low end, however a hi-flo cat is a good compromise between the stock cat and a midpipe.

Check this thread for info on hi-flo cats that people have and are using:

https://www.rx7club.com/forum/showth...hreadid=128667

If you have emissions testing (which I thought they did in England) then the hi-flo cat is that much of a better choice. Not everyone wants to smell like exhaust when driving their cars.

 

Thanks for the thread some useful info. It looks as though bonez wins hands down. I got a bltz nurspec catback and that on it's own is as loud as anything. I was a bit worried that with the noise I already have a midpipe would deafen me.

rgds

Brian

 

To be honest, I've heard my catback on a midpipe and it really wasn't that much louder than my Bonez hi-flo cat.

However, there are other reasons to not get a midpipe as there are other issues you need to be prepared to deal with in getting one.

My main reason for not getting a midpipe (aside from it being illegal in my state) is that during "good weather" months, I do drive my car to work sometimes. I cannot work in a professional environment smelling like exhaust. As well as my wife enjoys riding in the car and wouldn't want to be smelling like that either.

 

Hello Brian

A while back I was searching for a HF cat in Europe. Rotechniks in the UK sells the Bonez HF. I believe it runs around 450£. I spoke to a gentleman named Simon Kramer. I only talked price so, I am not sure on hp gains. It is the same HF that RX7.com sells for 495$. Alot cheaper than RX7.com after shipping and taxes.

Ant at Reworx or Jason at JT imports can get the new Knight Sport HF from Japan. It cost a bit more. Ant said quality was far superior than Bonez and has a nice hp gain over stock.

Inukai in Japan. Told me the RE-A HF is the best for HP - think it was 800 to 1000$ plus shipping? Never heard back from him for more details.

Thats all I know from outside the US.

Gotham Racing (in the States) has the best price 280$ ??

//Oliver

 

Bonez hi-flo cat sound like the way to go. Now how about wieght? Has NE1 tried to figure out weather the Bonez is lighter than stock? Or is it safe to assume that anything aftermarket is lighter than stock? I only ask because I recently removed my exhaust to pull the Trany and I was going to use a 2Ton jack to hold the dam thing in place so I could rebolt it. <----- LMAO 2Ton jack needed!!!!!

 

Hi Oliver,

Thanks for info. I know Ant very well. he is off to Japan today actually. I know about the knightsports, but I am reluctant to spend $600 on something that I don't know if it gives any substantial performance gains. Still trying to get more info on it. I here the re amemiya is very good yet again that price for a cat is crazy.
I don't buy anything from rotechnics anymore personal reasons. It just seems like there are plenty of exhuast manufactures out there with mid pipe downpipes and catbacks but not much hiflow cats.
What did you go for in the end ??

rgds

Brian

 

All the aftermarket high-flos are lighter than the stock unit.

 

I haven't purchased HF cat yet Brian

Ordered a rear wing and recovering from the holidays. Check your pm

 

I bought a used Random Tech hi-flo cat off the net - tuens out it was gutted and I got ripped off - it was basically a midpipe. I installed it and it was L O U D!!!! It's especially loud with a dp, non-seq turbos, and N1 catback. I went to Meineke and had them weld on their performance hi-flo cat for $150 - doesn't have a nipple for the airpump though. I gained a LOT of low-end and torque compared to the midpipe and it was much quieter - didn't stink as much either. Turn out that Dave at KDR said the number on the hi-flo cat is the same as a Bonez hf cat - I've had it for 1.5 years with no problems on a heavily modded FD - put about 6-7K miles on it.

 

Hi Brian I am Indeed Chris P from Fduk

 

go to www.atrperformance.com, where they will sell you their stainless steel hi-flow (with nipple) for $295. It's much lighter than the stock cat and somewhat louder. I believe that all hi-flow catalytic converters are the same base unit (makes sense if you look inside one- it's not something that most companies can manufacture). So, why spend extra for a Bonez, or whatever.

 

The ATR is "not" a hi-flow Cat'. It is a MP with a Magnaflow muffler welded in the middle of it.

Border Racing and Knightsports hi-flow Cat's will run anround $650 and the RE Amemiya is about $1,200 and can be purchasded through jt-imports.

 

Hi OC94Rx7

RE-A HF cat is good quality but very expensive.
I've got info about the HF Cat in the similar quality and cheaper at TAS.
I will e-mail you.

Thanks

 

are you sure about this? it does not look like a muffler plus it has the tube hookup for the airpump. I'm thinking about getting one because of the good price. 2nd option is to buy a MP and then get a catco hi flo cat from summit and weld it in.