Hey guys, I'm gonna fabricate my own 1980 rx7 12a exaust since I don't have $800+ to get a Racing beat exaust system lol. So I'm planing to use a pacesetter header with a magnaflow cat on 2 inch exaust pipes. Now I don't know what kind of muffler to use at end? Should I just get the power pulse muffler racing beat has to offer or is there a good universal one out there?

 

racing beat 2" universal muffler

 

^They don't sell a 2" universal muffler. But they do sell a 2" powerpulse muffler. Get that.

 

how about the rotary shack muffler? is that any good?

 

2.5
http://www.racingbeat.com/RX7-1975-1...rts/16025.html

 

The rotaryshack muffler is the RB universal just with a 2.5" (or 3") dumpy welded on one end.

It should sound ok (others have said it sounds good). Only problem here is they come in 2.5" and 3". Your system is 2". There will be a sudden expansion which kills velocity in the one area where you don't want it ie this far back from the engine where exhaust gasses cool and contract. It's actually better to swap to a slightly smaller diameter pipe back there. However since your setup is already 2", it's already too small to make good power anyway. Might as well get the 2.5" universal, throw it on and use it while collecting parts to redo your whole system in 2.5". Been there, done that, it works. But now I'm swapping to a long primary because it works better.

 

I run a pacesetter dual outlet header with 2 inch pipe all the way back to a racing beat "street port" muffler. it sounds good and offers a noticeable gain in top end power.

 

my rx7 still has the stock exhaust system with rust holes all over it. so I can still wait to get everything for my exhaust system. so going to A 2.5 inch exhaust pipe will be better than 2 inches?

 

Yep but don't use thinwall crushbent tubing from your local muffler shop. Get RB's thickwall 2.5" straight tubing and one of their 2.5" u-bends. Should be enough to get up over the rearend. Also a set or two of their 2.5" flanges and a couple of gaskets. Then chop the small 2" collector off your header and weld on a 2.5" section to match (flatten the 2.5" down to 2" tall and about 3" wide - chop your collecter to match the width).

I did this exact project in the rotary powered GLC and it was a big noticeable improvement in power while reducing the awfull noisy raspy tone it had at 2". It was headache-inducing before, so all around improvement. I think the raspiness was caused by the 2" tube never having a chance to expand and loose some of its super-sonic-ness, so the 2.5" definitely helped.

But I know I can go further. A long primary is next on the list.

 

okay I got it until you said chop off the collector and beyond lol. it got confusing real quick real fast at the end ( I'm Such a Noob)

 

pictures will be great! ( More Of A Noob)

 

Basically he's telling you to make your exhaust 2.5" by cutting off the collector of the header where it is 2.5" and welding on a flange.

FWIW I am running a 2.5" custom job with a Moroso Spiralflow muffler and a cheap eBay resonator (i.e. fart can) on the end, it's a little loud but not ridiculous.

 

Pacesetter is garbage. I had one on my last SA. It lasted 2 years before it rusted a hole through at the bend right out of the flange.

 

huh well that makes me reconsider on the pacesetter lol. so I'm doing a custom racing beat header. stainless steel exhaust pipes., a magnaflow cat, and at the end a Rotary Shack power muffler.
gotta remember that I'm running a stock 12a with the stock rebuilt nikki. in a couple of months I'm going sidedraft 45DCOE weber, and direct ignition, obviously I'm gonna add a carter fuel pump and Holley FPR

 

Those stainless pipes will ring like bells won't they?

 

If your looking for a cheaper alternative to RB mufflers, I have found Magnaflow to work quite well. I have two on my car that have lasted 15000km so far including two track days and plenty of hard driving. Its not incredibly loud either, maybe a bit louder than a full RB system. I still have the stock 12A and Nikki carb and even with 2" single piping it makes some good power. You should stay away from Pacesetter though. They use thin wall tubing for their headers and they will ping like crazy on a rotary. Also, try to use thick wall tubing for the rest of the exhaust as well. Something with a wall thickness of at least 14 gauge, preferably 12 gauge and don't use an oval presilencer like I did. The oval shape will vibrate and allow the pinging sound through a bit as well. When the exhaust is cold, I can hold my hand on the presilencer (a 4x9x14 magnaflow muffler) and feel the exhaust pulses at idle. Thats how strong the pulses are. A round muffler will deal with this better.

 

I have a pacesetter header that came with the car. No priblem except where the bends are coming out of the flange i can tell im close to bliwing a hole through it. Since my current exhaust is a hack job im replacing in next week hopefully. Header to a cat (piece of pipe with the cat body rewelded on it) straight back to a magnaflow oval muffler. 2.5"

 

well I'm going 2.5 inch stainless steel pipes that racing beat has to offer. I'm also buying their make your own racing beat header. Jeff20B gave me a good example on why to go 2.5" pipes.