Is there any major advantage over a 2 out vs 1 out exhaust for 914-6? Power or sound? Any reason to pick one over another?

The sound is, IMHO, better out of a 2 in 2 out can. It also depends on whether or not your engine is big enough to produce too much back-pressure.

My 2.7L E spec motor worked great with a 2-in/2-out was too much for the 2-in / 1-out. My 3.6 won't work with either one.

I thought about making a 2-in / 2-out with my own internal porting, but it was easier to use other solutions, like SuperTrapp or phase-9's...

But then I don't mind the noise.

twin pipe..........beautiful sound.
twin pipe if properly executed..........better power.
twin pipe.........looks great

had a nice twin pipe on my 2.7RS 914-6 and loved every minute of it.

now I have my '75 2.0L twin piped

Some twin out's can have a resonance at the mid range. Loud.

Dan, what are you running ? M&K GT3 ?

that is a custom made twin pipe on a stock 2.0L banana. 4 cylinder kind of rare

the one I had on my 6 was a partially gutted stock muffler with correctly placed twin pipes...there are several places to make the twin pipes exit. Some make it quieter, some make it louder, some give it a bit more torque...especially if the pipes are the correct length.

2.7L too much for the 1 out...why? My 3.0L on the 911 has 1 out...and I was planning on putting it on the 914 for the conversion.

I don't have the equation, but you can calculate the proper exhaust size, both headers and muffler. I went with what was recommended by several people different sources that know what they were talking about, 1 5/8" headers. However, I was sold on the sound of the Dansk sport 2in2out from my boss' car.

I'm using one in/one out X2.....although a crossover tube might help....3.0 six

Click to view attachment

I just installed a Triad 2 in/ 2 out and it sounds awesome. Mine displacement was on the small side so it was recommended to go with
1 1/2 inch headers.

I have a stock Euro 3.2 and i tried the two in two out sport muffler and it was way to loud for my neighborhood. It sounded like someone was bouncing metal balls off of the neighbors garage across the street. I took my car for a spin and noticed better top end power, but took it off anyway and put the single exit Bursch turbo muffler back on. Much quieter. Sport muffler went back on ebay the next day. Since then I have heard of silencer inserts for the sport muffler that are removeable for track events. That might have been the way to go.

I have the M&K 2in 2 out, It sounds great. But it resonates on the freeway and now most of the time I have the pass side capped and un cap it for events. Plus its more ... with one capped.

You probably get more top end power with the two outlet, but 90% of them I've heard have annoying resonance in the cabin. A few of them would just wear you out as the worst resonance came at cruising RPM's.

For anything up to and including a STOCK 3.0 the stock Porsche banana muffler is hard to beat. You might loose a little on the top end, but a little bit of restriction helps the low end torque.

Bigger and more open exhaust isn't always the best thing for the flat 6 engines, a little back pressure isn't a bad thing.

Great, thanks guys! Looks like the stock muffler from the 911 will be the way to go.