Geo

Yes, Magnaflow! Thank you!

I also have heard really good things about Remus, but they are rather pricey.

Mongo

Magnaflow is a good exhaust. If he is running a cat, he will not lose much low end power. I remember running a striaght through type resonator as a muffler with the factory catalytic. There was no change in low end power from what it felt like, high end I never really bothered to determine because I was wrapped up in the sound

Campeck

did you even read.
backpressure is bad. omg.

Mongo

You don't know that. Backpressure in same cases may even help combustion and compression. I won't go into detail on it because I haven't studied it much. I do know that any exhaust straight through that is larger than 2 1/4" diameter significantly affects respiration on the 8-valve cars, causing a loss of torque with little to no gain in the upper RPMs. And yes, I do have dyno time to prove this.

GOSANE

borla=glasspack (more mellow sound)
magnaflow= baffled and or chambered (more raspy sound)

any turbo benifits from as little backpressure as possible (how much noise can you get by with?)

bleucamaro

Next time, I'll have to put more emPHAsis on the sarCASm.

formerGMguy

Magnaflows aren't baffled or chambered. Unless they've changed design recently every Magnaflow I've bought has had a perforated tube running through it with a fiberglass packing.

Campeck

ok. i can see how it would affect compression. maybe make it .1 point higher or something. but the point is that any exhaust left in the chamber is going to slow down cumbustion, heat the air, and lose power. yes i do know. ive posted sheets of dyno testing before and you can't tell me that inlet charge dillution is going to help power...

Campeck

oh KAY

Geo

Stig, if you're talking to me, I can tell you that my info comes from someone who is an OEM engineer and used to work on the Toyota GTP engine program.

Geo

Actually, it won't raise CR at all. CR is a static measure. There is no such thing as "dynamic compression ratio" despite the Internet gurus who claim otherwise. Consult an automotive engineering textbook and you won't find that expression used.

Mongo

sorry Geo, I was talking to campeck.

Campeck, The design and engineering put into the 944 motor can only be improved upon through mechanical modification. If one is looking to gain more power out of an exhaust system for the 8-valve car, it's not going to happen there. When Porsche created the exhaust system for the 944, the header was equally matched and lengthened. The factory muffler really doesn't cause a restriction issue and I have seen cars put more HP to the rear wheels using the factory muffler when compared to other exhausts out there.

Now again, I'm not a pro at exactly telling you how backpressure can affect the 8-valve naturally aspirated, but there is some needed in the 944 to help pressurize the cylinders for proper combustion. That .1 point that you said it may add in compression is a tenth of a point. That is a difference in compression that could increase power as well. If you look at the cylinder head on the 944, you'll find that the exhaust ports and intake ports are matched to the diameter of the valves, proving there is little to no restriction relevant to the entrance and exit of exhaust and oxygen that feeds the engine.

Another thing to do in this debate is to ask someone with a 3" exhaust on a 944 all the way back that is straight through how the car feels. And, I'm quite sure he will tell you the same thing I'm getting at: loss of low end, small amount of gain in the high end. The 944 motor cannot make full use of a straight through design because the engine is not designed for high RPM, nor is the camshaft profile appropriate. But, then again, what do I know? I've only rebuilt a frickin' motor, and have constructed over 4 different exhaust systems already for 2 944s.... Don't mind me.

bart1

Speaking strictly of muffler durability, Flowmasters are much more durable than Borlas. My stainless Borla rotted out around the pipe on my Jeep. Not impressed.

White Pony

http://www.car-stuff.com/performance...5&skipped=true

LAWL chec out this muffler that came up for my '24....

Sounds like my ex girlfriend.

Travis - sflraver

I am using a supertrapp to tune in my "HP robbing" backpressure. It doesn't give you any more/less HP/Tq but it does move it around. I went with a more restrictive system to give me more power down low on my 86na autox car.
I am not going to join in the technical discussion about backpressure on the NA but it works very well for me and my application.