In my effort to get to weight I have started looking at running straight pipe with no muffler. Has anyone done this? If so what is the make diameter for the tubing? I have heard 2.5"...

Also, have people made thier own frankenstein exhaust systems or do race system exist to buy?

TIA

Blake

The OEM exhaust is metric, I believe - it's just under 2.25. A straight pipe is obnoxiously loud - I ran my car that way for most of a year before I gave in. One of the smaller straight through tubular muffler from Autozone works well, and is light. Welding in a cat delete pipe and slipping on one of those mufflers is all you need.

if it's too loud your too old.

well mine has one muffler like Eric said and it's still too loud.

I can finally hear my car over others when racing and it actually sounds like a race car for the first time in my life! I welded on a straight pipe in place of the cat and welded in a straight through dynomax bullet muffler to replace the Porsche one. Just take the time to mock it up, tack weld, check fitment and finish the welding.
I guess I'm not too old now! YeeHaa

I have two set-ups for my 944. I removed the cat pipe and installed a straight pipe there of stock diameter. After that I run a stock muffler section. I also have a straight pipe end which is stock, but no muffler at all. I ran both at Miller last summer. I found no power gain from the straight pipe and found myself faster with the stock muffler. It was not so much due to power, but I sound.

It seem strange, but the straight pipe was so loud I could not use the sound to judge my throttle position and RPM. It was very on/off. With stock muffler back on I could hear the engine more vs the exhaust and found it easier to control part throttle imputs and be smoother in the car. As a result I could attack the corners better and run faster. Odd right?

Well since I did not notice any power change with either set-up I continue to use my stock muffler. Weight is not a problem for me either. The other benefit is that a straight open pipe is really loud in the paddock. Those warm up times and trying to diagnose engine sounds is so much harder with an open exhaust. Idle with a stock muffler is really nice and makes it easlier to hear any engine noises like weak lifters or squealing balance or timing belt rollers.

I'm running a cat delete pipe and and an aluminum glass pack (freebie !), and my car is probably at least as loud as anyone in the RM region. Last year a Miata "converted" it to a straight pipe. It wasn't much louder, it just sounded more like farm machinery. If I were to do again, I'd invest in something to refine the sound a bit. Anybody use an "Aeroturbine" ? I've been considering trying one of their mufflers on either of my cars.

BTW between the cat and the muffler, there is a lot of weight to lose there. Somebody can chime with actual weight. Seems to me it's like 35#