I want to avoid a real mess, so I am not going to name a vendor, but heres the deal.....

I emailed a vendor asking about how much horsepower I would get out their pre-muffler and dual exhaust on a completely stock 3.0 sc. They came back with a claim of 22hp. This was a personal e-mail, not marketing materials. Beyond that, the vendors website points out that SSIs are a waste of money, and that a pre-muffler and muffler willl have the same effect.

Opinions on this? Personally, it seems very suspect. 22hp from a cat pipe and muffler? Hmmmmmmmmm.......

 

I went through the whole spectrum. I have a 1982 911SC. First I went to a test pipe. It sounded better but my butt dyno at drivers ed did not feel any improvment. I then did a pre-muffler. When back to the old sound and my butt dyno still did not feel any improvment. Now I have SSI's with a Dansk 2 in 1 out muffler. Better throttle response, and my butt dyno feels a difference at drivers ed. The rpm curve is smoother and I get up to a higher mph, quicker in the straight aways. The good thing is it is easy to sell test pipes and pre-mufflers so its worth trying them out.

 

That sounds like Joe's line. SSI's have been documented to be beneficial. Bruce Anderson's 'Porsche 911 Handbook' says SSI's on a 3.0L engine can get 17-22hp, and he has test data on a 3.2L engine that yielded 13hp (SSI's are starting to get small on the pipe size for a 3.2L engine, so the benefit isn't as great as on a 3.0L engine). I'm not disputing what the premuffler/muffler solution might do/not do for you, however, I would approach cautiously where someone says that SSI's are a waste of money, especially given how the SSI's work.

 

I just installed Brand "F"'s Pre-muffler last week (people know I've already mentioned whose I bought). Have been trying to get in to the dyno to see what (if any) gains just the PM made. I did the PM in order to make better use of the Steve Wong chip I am looking to drop in shortly.

I fully expect the combination of a PM & a better flowing muffler to yield better results than one alone, but I was also told that with 204 wheel hp (before PM), I shouldn't expect all that much from opening up the exhaust with only those 2 components.

As with any modification, your mileage may vary.

 

Please educate me. What is a pre-muffler? Is a test pipe something different? I have a cat bypass pipe (does it qualify as a pre-muffler and/or test pipe?) on my 87. I am planning on doing an exhaust and Steve Wong chip soon...

TIA

 

As Bill points out, the 3.0 SC's benefit more from SSI's than the 3.2 Carreras.

I have SSI's and a 2-1 Dansk Sport Muffler on my 2.7 911...major improvement in performance as noted by my butt-dyno (engine operates cooler also).

BA has stated on several occasions that a euro pre-muffler and sport muffler on a 3.2 Carrera will give similiar performance improvements to SSI's and sport muffler on the 3.2 Carrera. On the 3.0 SC's, SSI's are the way to go for real HP gains.

Of course, if you have the 3.2 Carrera, then you can get even more performance gains from a Steve Wong chip...but that's another topic for another day.

 

LOL,.....22HP from a cat pipe and single-in/single out muffler?,......not on your life,...

If the stock cat was plugged up and the muffler had some broken baffles, one might see a 5-10 HP change.

15-20HP is found with SSI's and a good sport muffler like a Monty.

 

As far as I know they are the same thing.

 

As I understand it...

Test Pipe = Bolt in straight through pipe only.
Pre-Muffler = open style non-restrictive "resonator" style pipe. The PM I got is open as far as the through diameter, but opens up like a Thrush or Cherry-Bomb style muffler.

 

Yep, premuffler - you need a little back pressure

 

Thanks, guys...