FDxc

i m planning to get the Bomb style mufflers, and new 3" y pipe this weekend, but i read some posts and it said that i wont get much unless i gut the cats and put in a midpipe.

midpipe is basically a pipe that goes through all the way to the engine right? Or is it for Turbo's only? i have 88' vert. If i gut the main cat, and leave the pre cat and put straight pipes, would i pass emissions? how much power would i be expecting w/ this setup? i have everything stock... (i'll have to get new intake in few weeks from T and R..)...

Thanks

oh yea and how loud would it be w/ this setup? I am just lookingn to get a mean growl.. i dont want harley's loud sound..

Coolidge

I think a midpipe is what replaces the main cat when you remove it.
You wouldn't pass emissions for sure, not a chance. You have an NA right?... I'd guess maybe a 20 hp gain.
It will be extremely loud with straight pipes. Ever heard a chevy with straight pipes? Like that, but probably louder. Very very loud with straightpipes!!

Also, don't gut your cat. Either replace it with a high-flow cat, or remove it all together if you can get away with that for emissions in your state.

rico05

More like a 10-15 hp gain for a full exhaust. A midpipe wll only add like 5-7 hp, and it only replaces the main catalytic converter. A racepipe (like the Bonez unit I am getting) replaces all 3 cats, and bolts to the header and to the y-pipe. It will be a little louder w/ a midpipe, but a highflow exhaust will definatly up the decible level. If you care about sound, get the midpipe, then get the Racing Beat mufflers www.racingbeat.com. And no, emissions are so gone! You will not pass at all!!!

vaughnc

3 cats?? On my vert I just replaced the pre-cat with a downpipe and added a performance cat to replace the main one.

rico05

There are "2" pre cats, and one main cat. It is really ilke one, but Mazda calls it two. The FSM says the RX-7 n/a has 3 catylitic converters.

Ryde _Or_Die

If your looking for all-out performance then your not going to pass emissions, simple as that. If you want the best you can get while passing emissions, I guess it would be to get either a header or a "downpipe", a high-flow main cat, and then whatever you want from there.

GTUsGUY

How about the header and presilencer made by RB? They claim that it doesn't make the car louder and it replace the 3 cats. How much HP will be incraesed?

Ryde _Or_Die

Thats a good choice right there. I can't give you definite answers but thats your best best. It is high quality, not too expensive, and gets rid of all your cats so gives good gains.

rico05

A buddy of mine has a Pacesetter header, no cats, and dual Dynomax 4 inch mufflers on his 89 GXL. He clams a 20-25 hp increase, but it sounds like a weed-whcaker on crack at WOT. Yes, a header and presilencer will not make that much noise, but as soon as you add a cat back, BAM! You got yourself somethin to wake up the neighbors with....

vaughnc

Yep. I'm thinking of putting in a presilencer on my vert as it's a daily driver. The HKS exhaust sounds good/deep - but too loud right now).

On the Turbo II - glasspacks but they're tolerably loud.

GTUsGUY

rico05, RB claims that their header, presilencer w/ their cat-back doesn't makes the car louder, they say that the sound is near stock.

Mobius

Screw midpipes. I had one and it sounds like **** and it basically sucks.

I have that racing beat system. Er, I think. I have no "cat-back" i guess.

Hey what the hell is cat back anyway?

As far RB goes, I have the full system from mufflers to header. Not loud but strong and good.

A VERY noticable hp gain. Especially with a cold air box.

rico05

Right, the header and presilencer, coupled w/ their cat-bcak exhaust, will not be any louder than stock. But slap an N1 on there, and oh yeah, it will be loud. Just maiking sure he realizes that. But me, I like loud! It scares away grannies and hondas!

Mobius, the "Cat-back" is just that. It is the y-pipe and mufflers, i.e. everything back of the catalytic converters. I have a gutted cat (basically a midpipe) and it sound fuller, not like a fart.

Mobius

I never gutted the pre cats so maybe that's why it was like fffffffffffffffaaaaaaarrrrrt.

LOL. I thought "cat-Back" meant that it somehow recirculated the exhuast back and in some cosmic way to boosted exhuast output. kinda of like fords SHO exhuast.

rico05

Ah. No the cat back is just the mufflers. I have gutted all 3 cats, so that is probally why it don't fart. It sounds sooooo tough when I really get on it. I just can't wait till next month when I really get my exhaust going!!

Jaybr

I just put the Borla cat-back system on my 88 n/a and it's as quite as stock just a little deeper tone. I know it's not one of the Japanese systems everyone like's on their rex, but for about the same price it's full stainless with million mile warranty.

I also have the Bonez superflo midpipe on the way which should make it a little louder

Taranis

I'm interested in the RP catback. If anyone here has one of these, please share your opinion.

Jaybr, you'll like the bonez superflo.. and it does make it quite a bit louder..

duffles

i just put on the bonez superflo, a little louder, but definitely worth it, you will turn some heads when you get on it if your cat-back is decent.