What are the performance and sound differences between a catless mid-pipe and a high flow cat without a resonator? I would be pairing this with the stock exhaust.

 

I dont know for the stock exhaust, but with my aftermarket, high flow cat is like 3x as loud. no cat is 10x as loud, It sounds like a race-car inside the cabin. (everyone who rides with me comments on how loud it is)

Performance is great, smell is very very bad.

Depends on where you want to go with your mods, are you searching for all out performance or for some performance with the benefit of no CEL and quieter?

Personally I would go race-pipe, I like the noise. It cuts out the middle step of you finding out that high-flow cat isn't enough power and you want more.

 

I wish you could hear my car in person though.

Ive had my friends drive it for me with the hih flow and catless, and with high flow its so throaty and awesome with the RB muffler. With no cat it sounds so damn exotic and fast. Daddy like.

 

Difference between a hi-flow cat and catless pipe is only a few hp, at most. IMO, the very slight performance gain is not worth the excessive noise, possible CEL, smell, etc.

 

Depends on your mod ideas down the road. On an otherwise stock car the hp difference is small.

On a modded N/A car the difference is larger,

on a turbo/sc/nitrous car the difference is defiently there.

 

Not really. On a otherwise stock car you are talking about maybe 1-2 hp. On a modded N/A car you are talking still about 1-2 hp. Even on a FI'ed car you are talking about >5-6 hp difference between hi-flow cat & catless midpipe. We tested these on my car, when I was Fi'ed the gain was not that big. Definitely not worth the down sides

 

nice,

thanks for the into

its always good to get correct info out there

 

Ok... So im eventually going to be doing all the N/A mods. Not planing on going F/I for a few years. My budget isnt large and I already have a CEL from cutting the resonator out. Thats why I have decided to change my CAT-midpipe setup, because If Im gonna have a CEL might as well get some sound and power out of it eh? I would go with the high flow cat but they seem to expensive in my mind. When I could just get a resonated straight pipe for half the money and get a few extra HP. But I dont know how overwhelming the smell is so thats why im asking... Thanx for all the info so far.

 

unfortunately all that aftermarket sh-t is just that, sh-t ... but only because most people are too cheap to pay $1000 for a true hi-flo cat pipe that can flow like an open pipe and take the rotary heat

 

I run, when I have it installed, a RP Supercat w/ resonator and the stock exhaust. I'm VERY biased in the matter as I am pro power and anti sound. Non-turbo, a rotary is a pretty loud engine, and I don't think I could handle a mid-pipe. I plan on replacing the exhaust to change the ton/appearance, but I'm going to try to keep the <5k rpm sound down. I just need to decide on which.

One other consideration is cost. My supercat wound up being close to a $500 install as I got the cat, the hardware, the gaskets, and had it cut and a resonator put in. Bare bones, a hi-flo is probably 300$ mostly due to the catalyst cost. A midpipe is more in the ~120$ range. With a stock exhaust, it might not be unruly.

 

for us cheap folks--which i am a proud and working member!, one small thing you can do is to knock out the part of the oem cat that is behind the o2 sensor(about 50% of it is)--that will open it up a little.
Myself---i just bought a midpipe and will be putting it on only for track events. Mostly for the sound. Got tired of sounding like a wimp coming down the straights.
Ray-- one of our members actually had a small loss of hp per dyno with one of the more popular hi flo's--go figue. he is na of course.
olddragger

 

Also remember that removing the cat you're doing some serious polluting and annoying the **** out of everyone around you (and I'm a right winger not a tree hugger). Knocking out the cat may sound like a good idea but that's cancerous stuff inside. Buy the new RP cat and be done with it.

 

You're going to give us all ovarian cancer and most of us don't even have ovarians.

 

Correcting my intentional incorrectness does not improve the mockery.

 

Just an FYI, you aren't supposed to get a CEL from just cutting out the resonator. There are plenty of people here running cat only with no CEL. Are you sure you cut out the resonator ?

 

Quick question on the whole catless thing. I presumed the big advantage of going catless, beyond the slight improvement in power via increased flow, was that you could lean out the top end of the RPM range without having to worry about the EGT's cooking the cat? Am I wrong in thinking this?

 

Yes I cut out the resonator. The CEL is from the o2 sensor I fried during the process of welding it back together. Or at least thats what the dealership told me...

 

You're lucky if that's all you fried if you didn't pull the ECU wiring connectors and battery ground loose first ...

 

I believe high-flow cats (least upper tier ones) are pretty hard to cook and the temperature where you would cook a high flow but wouldn't cook a catless pipe is so high you don't wanna be there anyway.

I know team uses a $800-$1000 knightsports cat, but does anyone sell something just as good that can be welded in, rotarygod posted a pictured a while ago of a high flow that looks like you just weld it in, can't find it ATM Fred can you pop in an post what i'm thinking of?

 

HKS has one. It is pricey, but arguably top quality on the market. Like the rest of their products the welds & the cat unit & the flanges (are thicker & of higher quality) are top notch.

 

sually you take the pipe off before you remove & weld stuff on & off. The O2 sensor is a relatively cheap fix. You should just get another one and do away with the CEL.

 

Well my dealer said the o2 sensor is 220. And on my budget i cant spend 220 on clearing a CEL. Any way I could get it cheaper?

 

I am gonna try a an all metal high flow CAT on my TurboXS catless race pipe. This one is from Magnaflow #59959, http://www.putfile.com/pic.php?img=5370215 and http://www.putfile.com/pic.php?img=5370213 (also made/supplied by other companies).
Don't know how well it will work. but I am willing to try it out and see if it can handle the exhaust temperature from the Renesis engine. When I am done fabricating the new set-up I will let you know how good/bad it is. I am fitting this with flanges so as I can swap the CAT for a straight pipe in a matter of minutes instead of having to remove the complete race pipe. This should keep me street legal and the exhaust gasses won't smell so bad, I hope.

 

Incorrect statement, I imported a stand-alone cat (not from Jp) and welded it in a custom exhaust system and your cost numbers are off.

I've never posted pictures of the actual install, the only people who know what I have are myself, the manufacturer's head engineer, and their distributor that I bought it through ...

 

How uncharacteristically cryptic of you.