Road Race Muffler
 

What kind / size / pt# / muffler are you road racers useing on your IT-7 / IT-A 79/85 RX-7s? Thanks, DICK

Series 40 Flowmaster on one car, some Dynamax POS on the other.

EDIT: Both over-the-axle with mufflers behind rear end; RB headers.

Dynomax. Not sure on the model but it's not the POS. Keeps the car under sound regs and is on it's 4th season. Cheap, effective, straight though muffler.

I am using a small rectangular Spintech muffler. no sound requirements where I race but I don't know how loud it is either. it is a straight through type similair to the flowmaster with no packing to deteriorate.

I don't run IT, but I think the MazdaSpeed Mufflers work well, they certainly last. I am using a 3.5" DP/ RB presilencer/3" pipe/ Apexi N1, flows well, and meets sound even at Laguna.

Pos???
 

Ok guys! I looked at the Dynomax web site and there nothing about "POS". So tell me what it means. They show both a round welded, an oval welded, and a bullet shape race muffler. Which one fits / works / last? Thanks again, DICK.

Chris was referring to his as a Piece Of Shit. We use the round welded on our ITS car. We've also used their bullet mufflers on street cars. Save your money on that one. It's not much of a muffler.

Pos Again
 

I should have known! Chris! I owe you one! POS is right on the bullet model. Muffler in name only. But their ad says that. Thanks again for the advice. DICK.

The flowmaster I have used a lot in the past.. Long collected 2" into a 3" under the axle, and into the 3" flowmaster.. using a 3" turn down.
Worked GREAT...... Until I backfired and blew a triangle shaped hole in it.. about 2" per side.
The first flowmaster had baffled inside break loose.. and I shot one out the tailpipe.
Both were after about 6 months of HARD use. (Autocross, TONS of illegal street racing, and track events, as well as race)

The last muffler I had with that combination was excellent. Mellow Loud tone, not tooooo loud.. but It did get me pulled over 3 or 4 times. It was a SS Edlebrock 3" in 3" out muffler.. it was for RVs I think. But it was nice. Had a oval shaped chamber in the middle.. and was ceramic packed.
Pulled out of the muffler shop after having it welded on (before the garage was done) and it was QUIET... I laid into it through 4th.. and it was MUCH louder, because I blew the ceramic out of the center area. HOWEVER. After that it never got louder.. and I used it for prolly.. 3 years.
Made 101.7 HP and 101.4 FTlbs of Torque on a Dynojet.
The RB long collected system It was replaced with the same night after the 30 minute swap out...
Made 102 HP and 99 FtLBS of Torque.

This was a 149K mile TIRED 12A.

The torque loss was noticible. It didnt pull through a very windy series of corners I go through every night OTW to work as well as it did before I changed exhaust.

The Mazdacomp Muffler is great.. but HEAVY. And loud as well.
The N1 as Carl has.. DO NOT use the 3" on a NA. TRUST ME.
It is TOOOOOOO Loud.
Dont even think of it.
It will make you sick it is soo loud on a 13B na with a mild port.
I didnt think it would be as loud as it is.. but OMFG it is loud.

I am prolly gonna take the RB muffler off the ITA car and go with a Dynomax SS or ceramic packed with a 3" turndown. Not because I like the thing loud.. but because the RB muffler is HEAVY. The pre-silencers on the long collected system weigh 36 LBs alone. I replaced them with some mild steel pipes that I can lift with one finger.

I'm very happy with my Dynomax(4"). It's been cut open and filled with SS packing. THe fiberglass packing burned up. It's a little too loud. I hit 104db a couple of times and was black flagged. I've got to rig the exhaust pipe so I can point it away from sound control. I'm running the SDJ header, full 4" exhaust.

I should add both mine are 3". The series 40 system I haven't had on track yet in it's current configuration, but that muffler with a horrible system and presilencer was quieter than my street car. The Dynomax system is really quiet at idle, and could even pass muster on a street car. It doesn't get really loud until 5-6k RPM. I don't know about sound on it, but on another car at another time it passed. I think it's the welded round steel setup, but I'm not sure; it's definitely not a glasspack/straight thru. I'm not very fond of it, myself, but if everybody else likes it don't listen to me. ;)

Not ITA, but on my Pro7 (stock manifold) this is what we use (round welded), and the car is almost street ar quiet ( 89 DB). I anticipate using it on my ITA car as well.

Marcus

www.justmagnaflow.com

Figure out what the largest size is you can fit under your car. They will most likely have something close. The larger the can size the more it will muffle the exhaust and get you closer to passing sound. I could tell you what size to get for a 2nd gen chassis but I'm not sure on a 1st gen.