garrett376

I wonder if the primary is a simpler design to modify, so Fabspeed convinces you to get rid of that one because they sell a replacement... until someone does some kind of flow testing, I don't like to believe information from people selling things

The muffler is loud... my suspension arrived today so I may have the chance to do a sound clip. I have been told, by PC2 as a matter of fact, that my car is way too quiet vs the other race cars!

JasonAndreas

I think this is one of those situations where you ask, "What would Linton do?"

PC2

It was quiet but that was before your modification to the primary. Now all you have to do is drive it like a race car.

DarrylH

If you could afford to do what Mr Linton does... (OT, sorry: Man, I wanna see that Humpty Dumpty in the flesh someday.)

Cupcar#12

wwld - (What Would Linton Do) - He posted it actually - a carbon primary with Ti internals & a carbon cup secondary bypass tip (all high temp carbon resin) - if i remember correctly.

the best thing to do (if you want to modify your muffler) is to open it up - cut out the internals and replace the two perforated pipes and diverters with a single straight perforated steel tube. Everything is deleted except the perforated tube in this design internally. This is the design of the 964 Cup muffler that the factory used when a muffler was required in the later 964 series years.

fstockcarrera

These cars require almost no back psi. The most rwhp is achieved with all bypassed cat., primary and secondary, Cup air box mod is good for another +4 rwhp. The europremuffler w/ all else the same yields +4 RWtq and - 3 rwhp. . I did the dyno work last year on a blue printed 964 m64-01 motor. Adding back the secondary to contol noise looses 9 rwhp.

Bob

pete000

I would like to some how fit the whole 993 system to the 964. It is a much better design.

Cupcar#12

BTW - a FULL B&B system (Headers - Muffler) yielded only + 3RWHP - small for the cost

the 993 system can be bolted on but you loose your heat as the exchanger tubes do not line up (I', sur e you know that, and I'm just talking to myself )

fstockcarrera

You don't need the 993 headers loose the cat and the primary for a net rwhp in the range of
+ 20 Bob

forklift

Sweet! That's what I have.

Bob, do you know how loud (DBs) it is to run w/o the cat and both mufflers? I like the idea of taking off the secondary also for more power and less weight. Not sure if I would get kicked off of Summit Point or not.

Thanks,

Jim

fstockcarrera

I have run w/ out both @ sumitt. I run the secondary only @ Lime Rock
It is very loud
Hey is your avatar turn 10 @ Summitt

forklift

Cool, thanks. I think I will check that out but my neighbors won't like it. I ran behind Bill M. at VIR and it was loud for sure, but not that much louder than a Harley.

Cupcar

B&B, the exhaust system company, published flow data on the various parts of the stock 964 exhaust system and here are the results:

Catalytic converter 442 cfm (cubic feet per minute)
Primary (rear) muffler 396 cfm
Secondary (side) muffler 462 cfm

So eliminating the most restrictive primary muffler makes the most sense, the catalytic converter then becomes the biggest resistor to flow.

This data substantiates the Fabspeed claim that the primary muffler is the most restrictive.

FotoVeloce

I recently did the primary bypass. Nice improvement in the sound, I *think* a little more peppy per the butt-dyno but I want more MORE! So next is the cat.

Thanks to some of the WORST manufacturing I've seen in an aftermarket part the FabSpeed primary went back to where it came (USA.. hm.. I have my doubts). So.. in staed I had a local muffler shop cut out the muffler and weld in a section of straight pipe. I was able to re-use the stock bracket and I got a 3" clamp (a really nice one.. nicer than the ones in the FS kit, IMHO) for free from the shops scrap pile. For $60 they made a jig to line up the outlets, setup the stock pipe, cut out the muffler sized a new pipe and weled it in. It looks ick but sound slick!

So the money for the primary will got for a cat bypass. I don't trust Fabspeed at this point. What are my other options? Does Dansk make one and is it any good? Any others I should have the shop I got the primary from know about?!?

THX!

fstockcarrera

The Dansk pipes are good close to Oem. Bob