Hey Mokken,

Happened to buy a 300XS that had originally had an OS 160 FX installed but the motor had been sold before I got a chance to buy it with the plane.

I picked up another 160 with a Bisson muffler and found out that the "can" portion of the muffler was to large to fit in the cowl without some major cutting...

Picked up a Slimline muffler for the 160 and had no problems fitting it into the original muffler cutout without additional cutting....

So in this case it wasn't the pipe length but the can size that made my choice Slimline!

Bill