Works great, Borla's are straight through design so you're not going to lose much power if any. However, you will bring the noise level down and keep the Five-O off your back.

 

The manifold for the stock 20b twins is very restrictive compared to a tubular manifold for a single. That in itself will cause changes in the way your exhuast will sound. Rxman720b made a comment that his exhaust note changed when he replaced his twins with a single set-up.

 

sweet car dave

 

Sounds good. It isn't too quiet, is it? I don't have an RB on purpose... (I like to hear my exhaust)

 

Even with the Borla and a stock cat-back on my car (while I waited for the RB twin tip to arrive), people couldn't stand to be in the dyno bay with my car. After the first run, the only people left were me and the operator. It was quiet when it needed to be (cruising part throttle), and loud as hell when it needed to be (WOT).

 

I'm slightly confused here Jim. At first I got the impression that you were touting the Borla muffler welded onto a midpipe as a very quiet piece.

But here you are saying that the Borla muffler/midpipe combined with the stock catback was loud enough to drive everyone out of the dyno bay?

I'm looking for the highest flowing but absolute quietest cat back available for the FD. Any suggestions? I won't rule out custom made stuff.

 

It is, and I was. It toned down my non-sequential car substantially at idle and part-throttle cruising. I no longer had to cringe when I came home late at night and wonder if I was going to **** off my neighbors, or worry about being followed around by the police, or listen to the drone of the exhaust at highway speeds.

At WOT in a dyno bay enclosed on three sides.

Yes, it was plenty loud at WOT, but not nearly as bad as it was before. Before, Dagley's could hear me coming when I got on it after turning onto the main highway 3 miles from their house. After the Borla and RB twin tip, I had to be on the access road to the house (about 1 mile) before they heard me coming.

Three Borla XR-1s in series. That's what Brian Richards (Mostly Mazda/M2 Performance) ran on their race cars.

 

Thanks for the reply. I'll do some poking around.

 

if you don't want to do your own welding (this is stainless steel in most cases), you might to consider the SR resonted mp, or the RX-7 store resonated mp....I have little very droning with my SR, but is loud at WFO....I'm getting alot of creep in this cold weather as well

anyway, none of these alternatives compare to the ultra quiet set-up David seems to be enjoying from Pettit....it sounds like a high flow cat and large resonator chamber

btw David, just curious, did Pettit refuse to take pics of the engine building and installation process? that would have been cool to see, kind of like a shortened version of Jim's thread

 

Wow, how much does the stock Cat quiet the exhaust? I have a DP and custom CB (3 inch pipe, with a Magnaflow mufler w/ 4 inch tip) and its pretty quiet...not much louder than stock at idle (well stock with DP cause it came with the car) and not too loud at WOT either...not IMO anyway.

 

alot....that's why it is so restrictive

anyone who has driven/owned a bone stock FD with the stock cat-back as well can attest to how mild the exhaust tone is, even at WFO

 

I keep seeing you type WFO rather than WOT... what does that mean?

 

wide ******* open? thats all i could come up with..

 

Sounds pretty good. Too bad I'd lose the ability to backfire and blow flames on demand

That's what I was wondering... I knew what he meant, but couldn't figure out what it stood for.

 

No, Pettit didn't refuse. They sent some pics along the way, but remember, two hurricanse occured during the build and this threw them off quite a bit.

As for my exhaust setup, I have a downpipe, Pettit resonated midpipe, and a Thermal Exhaust. The car is definately much quieter than Red RX7s. I used to have an Edlebrock muffler welded onto the midpipe and this substantially reduced the "droning" of the car, but the rotary engine kept torching the inside of the Edlebrock and steel wool in the inside would break loose. The Pettit unit is okay, but I'm still getting some resonation at lower RPMs (the Edlebrock was just the opposite). So, I'm thinkin about swapping the resonated mid-pipe out for a high flow cat.

 

Hmm... sounds like an acronym for **** rather than cars.

 

old school term, my apologies to the young-ins....I grew up hearing that term

"WFO" just sounds so much better than "WOT"

 

Know I'm chiming in a bit late with the Borla/midpipe thing...I first started out with a resonated midpipe from Pettit waaaay back when I had the stock twins. Very quiet. Switched to a single turbo. Very loud. Slapped a Borla XR1 Sportsman in the midpipe in place of the resonator. Much better. Still drones a bit. I use a GReddy Power Extreme for the exhaust. I believe, however, that either the GReddy or the Borla has worn out (Borla's over a year old) and the GReddy is about four. I know Pettit uses the older SP exhaust on their Banzai three rotor and it was dead quiet. Even in the shop. I have a feeling the three rotor's exhaust pulses also have an effect on perceived noise.

 

The last part is very interesting. If you run all those mufflers in a series like Brian did, won't it restrain power quite a bit?

 

Nope. These aren't baffled mufflers we're talking about, they're a straight through design.

http://www.borla.com/xr1.sportsman.o...7216.52.28.146

 

So what does it mean?

 

Wide ******* Open = Wide Open Throttle

 

Hey, hate to interrupt this neverending thread but do any of you guys know if a 20b can be just dropped in to an FD using the stock 20b ECU and stock FD accesories? I know you need a custom engine mount. Does anyone know if the FD turbos will bolt up to the 20b exhaust manifold without reworking it?

 

The turbos would be too small and the manifold would not be compatible on the account of the extra rota.

 

Why not toddle on over to the 20B forum and ask there?

https://www.rx7club.com/20b-forum-95/