ronarndt

Am debating whether to go Pettit resonated midpipe or hi-flo cat. For those with the Pettit resonated midpipe, how much"droning" is there at turnpike speed? I had a RB resonated midpipe on my FC and finally took it off and gave it to rarestRX, cause I got tired of the headache-producing droning noise. Also- where I drive the cops target high profile cars if they are loud. I have gotten off with a warning a few times when they notice I am old enough to be their father, but I really do not want the attention. Any opinions on flow difference between the hi-flo cat and resonated mid-pipe?
Ron A.

silver93

HF - pick up HP, not as much as a MP. quiet, legal, no smell.

MP - more HP than HF, generally lose a bit on the low end, pick it up on the high end - louder than HF, smells.

personally, i have a MP with a borla resonator in it. love the sound, like the power - but hate the damn smell. i'm always considering a HF because of the smell.

ronarndt

silver93- Yeah- I had forgotten that smell! My 2nd gen had the same stench. Not sure if I want that again. Thanks for reminding me. Ron A.

weaklink

yah smell-my neighbor came over and bitched because I was trying to lean out the idle in my driveway. Said her bedroom had filled up with exhaust. Guess what? She was probably right!

911GT2

Then theres the issue of severe boost control issues with a mp. You'd need a ported wastegate, and a decent contoller if it's to even be driveable.

My personal choice is the high-flow because of all of the above reasons, and the emissions in MA.

ronarndt

weaklink- Love it! Loosiana woman be complainin cause her bedroom be fillin up wit exhaust! Wat dat bitch bin eatin? Gumm-bo? Wat she look like? An why she be blamin your pore lil RX-7 for her mizry?

Anyway- appreciate the advice. I probably will go with the hi-flo cat.
Ron A.

r0t0r-rooter

I have a ATR hi-flow cat for sale if you need it

crazysuprakid

I've got a M2 Downpipe, with a Bonez Hi flo cat and stock catback and still get the very bad exhaust smell inside and outside the car.

the_glass_man

iTrader: (2)

This is a good site that can show the differences between the high-flow cat and mid-pipe horsepower and torque.

Click Here!

rynberg

I have never believed the accuracy of that dyno comparison. The only real comparison would be to do a run with a hi-flow, replace the hi-flow with a midpipe and run it again on the same dyno on the same day, with the same conditions.

KevinK2

No it's not. Wael had ign problem from 4500-6K during that mid-pipe run. Here is his 'good' earlier midpipe run.

http://www.efini.net/dynoplot.htm

inis

if you are at higher altitude, you wont have boost spike problems (or shouldnt anyways). I have a mid pipe with an hks turbo catback. i love the sound. wouldnt trade it for anything in the world. As long as you dont get a rediculously loud catback, it will be fine.

plus, you get the kick-*** flames. the only smell i ever noticed was burnt leg hair from the people standing behind me in the parking lot.

kwikrx7

Like others posted, if you go with a resonated midpipe or a midpipe with a Borla inseRT and as long as you go with a quiet exhaust like the RB dual or HKS turbo - you should be ok. If you have any Apexi N1 or GT exhaust it's going to be loud regardless. I had a midpipe with all the bolt-ons, streetport and non-seq and it was smelly, lacked low-end torque, and friggen LOUD. I switched to a HF cat and gained an incredible amount of low-end torque all the way up to 6K rpms and it didn't smell as bad - muh quieter. You'll lose some peak HP up top, but according to my butt dyno, the HF cat in my car proved much more powerful in the low/mid range.

matty

THERE MIGHT BE MORE INFO ON THIS TOPIC THEN ANY OTHER TOPIC ON THE FORUM.

AgentSpeed

Do you have your air pump still? I've been considering both myself but still haven't made my decision yet. Will removing the air pump clog the high flow cat???

aimedhigh

I have had both set up's on my single turbo 3rd gen.
RB resonated Midpipe with Cat Back
RP HF Cat with cat back.
I prefer the cat because, I did gain more low end, the smell did decrease a lot. There is still a faint smell if you are behind the car but nothing offensive. The Cat was a little quieter at highway speed than the RMP but at idle sounded the same. I dont drag so I dont miss the MP much.

Mahjik

iTrader: (1)

kwikrx7 sold his car.

As for the air pump, there is no real hard evidence to support in either direction that removing the air pump from the cat makes it clog any sooner than with it plugged in.

However, you will NOT pass emissions testing if you have that in your state without the air pump hooked to the cat.

BTW, I'm also usig the Bonez Hi-Flo. At startup, it does kick out quite a bit of exhaust similar to a midpipe. However, it doesn't take long to warm up and quit stinking.

DaPlaya96

i see that everyone is going for the hi-flo.. i have a midpipe on and its sooooooo LooouuuuD and very stinky.. i'm thinking to go hi-flo as well.. i hope it isnt as loud and stinky..

ptrhahn

iTrader: (9)

Only problem with a hiFlow is, if you have the PFC, it doesn't opperate all of the air injection systems the way a stock ECU does, so it will basically eat your expensive cat up in a couple years.

ZeroBanger

I had a HFC for a while then went to MP. under 4500 rpm you cant even hear the MP, the noise level is more dependent on your catback than the MP.

with a stock engine I noticed no loss of low end with the MP, with my ported engine there is a noticeable decline with the MP vs HFC. The smell is bad in the mornings when I start my car, other than that I never notice it.

the MP lets the car boost so much easier than with the cat.

Mr rx-7 tt

iTrader: (5)

Your car will be faster with a midpipe/resonator. It makes more power from 4000 up...Your car will have better low end response with a cat but you won't notice.
With a cat you won't have the fumes or the brown residue on your bumper that you have to clean with liquid glass...

DaPlaya96

hmm.. im just gonna put a resonator in my midpipe.. hopefully that'll make it less loud... im thinking thats why its sooo loud right now.. i guess ill deal with the fumes.. which isn't too bad

Mahjik

iTrader: (1)

Interesting you say that when several people have already commented that it is noticeable.

Flybye

I did NOT notice a decrese in low RPM power at all when I went from the cat to a midpipe. If anything, all I noticed was an INCREASE. I mean think about it, your turbos will be spooling faster throughout the entire RPM band without that mess stuffed between the turbos and the catback. Then again, I don't have a dyno sheet to show hard proof what is really hapening.

Some may get a 4500rpm boost spike, which is easily fixed by adjusting the prespool. Some may have boost creep, which can be temporarily controlled by installing a restrictor plate between the DP & MP. I don't have any boost creep at all, and I have a nice solid 13.5psi all the way to redline, but I have an old Borla cat back.

GarageBoy

No Emissions, go catless! (unless you don't like the smell)