C-Westin

I've been having a exhaust leak for a while now, and it's been messing up my idle big time. I get a lot of backfiring when coasting in neutral, and sometimes the car dies.

i've finally found that i have an exhaust leak between my Catback and my Cat. I have an HKS Carbon exhaust with stock cat. I've tried replacing the exhaust gasket, but it hasn't helped at all. i'm using two gaskets right now which is better than one, but it still leaks.

i just ordered the PFC which should be coming in by the end of this month. i have an 3" ATR downpipe and midpipe. I plan on putting in the DP, but i don't know if i want to put in the MP because of boost creep.

i'm trying to decide if i should get a Hi Flow Cat (Bonez, NTech, or Gotham Racing) or if i should just use the MP i have with the PFC.

Will i have any problems like boost creep with the PFC base map and the MP, DP, and Catback? i don't want to put the MP in if i have to take the car to a dyno and have it tuned.

Anyone know if the Gotham Racing Hi Flow cat is any good?

CowsniperRX7

iTrader: (3)

The N-tech hi-flow cat is working great for me. I had a big gap between the downpipe and hi-flow but it was fixed by using 2 gasgets.

Maybe 3 is pushing it.

Mahjik

iTrader: (1)

You do realize that you should get the PFC tuned right? The base map is leaner than the stock ECU.

Any time you open up the exhaust (fully without cats or other restrictions) you run the risk of boost creep. However, it's not definite that it will happen. Every car is different. If you won't have the money/resources to deal with boost creep (should you get it), just get a hi-flo cat.

crazysuprakid

Well i have the bonez unit with a m2 downpipe and stock catback. Overall performance seems to be improved but the stock catback is restricting it still. Many people have talked about smelling like exhaust when you get out of the car when going midpipe. I feel it's the same way with a hi flow , still fairly smelly. But it retains the air pump and should be emissions compliant.

SleepR1

I have Bonez Downpipe, High flow cat with Racing dual tip catback with Power FC. NO boost creep or spiking. Highly recommended.

C-Westin

I don't have the time to get my PFC tuned, so i'm gonna go with a high flow cat.

I've heard lots of good things about the bonez cat but it's quite expensive. i've only seen it at rx7.com for $500. Anyone know where i can get it for cheaper?

If not, i've heard the NTech one is not bad, and it's on rx7store.net for $320 which is a much price than the Bonez one. The question is is the quality/performance as good as the bonez one? Also, in the description, it says that it can retain the air pump with some modification...is there really any modification necessary, or is it plug and play?

I've only seen one thread on the Gotham Racing cat, and the people who had it said it was pretty good. It's the cheapest at $299...anyone out there have any experience with this hi flow cat?

JOHNBOY

I have just had a bonez added, and have noticed that the inside of the car has an exhaust smell. If it is not a leak, and you can live with this, I may be selling mine in the near future. It has only done 300 miles. I paid $500 for at ( RX7.com ).

johnchabin

iTrader: (2)

I have the Bonez hi-flow cat. I passed emmisions the first year (Colorado), and am due again. I'll post the results after the test. I need to change plugs first...

Mahjik

iTrader: (1)

The Bonez unit is expensive, but well worth it. I have heard good and bad things about the N-Tech unit, mostly good. One thing about the N-Tech is that you need to do your own piping for the air pump (I believe).

C-Westin

For the bonez cat, does it really smell as bad as everyone says? and does it smell for everyone who has the bonez cat? or is it just in some cases?

Also, does anyone know how much modification is required to get the air pump to work with the NTech cat?

Mahjik

iTrader: (1)

Mine only smells at first start up (when the cat is cold). Once the cat is warmed up, no problems.

C-Westin

Anyone know if the NTech has the same problem that people with the Bonez Cat are having...the bad smell coming form the exhaust, and the inside of your car smelling like fuel?

cuz if not, i'd rather get the NTech one because it doesn't seem like the bonez is worth the $500 if it makes your car stink...and what's the point of making it bolt on with the air pump if it doesn't do anything about the fumes?

CowsniperRX7

iTrader: (3)

I have the N-Tech and my exhaust stinks but it doesnt get in the car and it is not nearly as bad as a midpipe.

Silex

Why not just rid the dp and gut the main cat and leave that sucker on so that you retain the full dp and mp design but if you ever get pulled it will look legal with the gutted cat?

gohorns

get a $100 midpipe and have a $70 catco converter (summit) with hookup for airpump welded in...custom hi-flo cat

kwikrx7

I got a $100 midpipe and had Meineke weld in a hi-flo cat - works great.

Oracle

C-Westin...Either way you decide to go you definitely need to have your PFC maps tuned. From the dealer, the base maps are not set to match the appropriate a/f ratios to match your aftermarket modification (or stock for that matter). Also, you will almost certainly see boost creep of some sort. With un-tuned maps you know what will happen in the near future. Any competent tuner (and I stress the word competent) should be able to adjust your maps to compensate for the increase in airflow. With an accurate wideband a/f meter this can be done without the use of a dyno. Just be sure you fix your exhaust leak before you use the wideband. The leak can affect the readings.

You are trying to run "safely", not trying to make your maximum hp.

Look up either Steve (Pluto) or I if you have any questions. We'll give you any advice we can.

C-Westin

Thanks Oracle. Basically, my main objective is to get rid of the exhaust leak to see if was really the cause of my unstable idle problem.

If i don't need to switch my stock cat to a hi-flow cat or a MP, then i'd rather save my money. But i'm having problems fixing the leak. I have a brand new exhaust gasket. But with the HKS Carbon exhaust, the new gasket, and the stock cat...i get some major exhaust leak. i don't know why.

the positioning of the pipes aren't flush, so it migh just be the way the exhaust is hanging.

part of the connecting flange on the bottom is slightly cracked...so that might be the cause of the leak.

Oracle, if you have any suggestions as to how to get rid of this leak, or diagnose why even with the new gasket its still leaks...that'd be great.

btw, are there any "competent" PFC tuners in the East Coast? i'm in Central Jersey...if i could find a knowledgeable PFC tuner, i'd go get my car tuned.

Oracle

I know this isn't the fashionable thing to do, but you could always have the two pipes welded together. Either that or you could re-weld your exhaust hangers to compensate for the discrepancies between the two.

I discused the tuning matter with Steve, and the only person he can think of to recommend would be John Durante. You could try looking him up. Or you could meet us at the RX-7 Revolution in April and Steve can take care of it for you.

T88NosRx7

iTrader: (1)

hmm.....