I have a Magnum 120 4 stroke, putting it in a Cessna. I need to use a longer exhuast pipe to exit the cowl. Where can I get this? Also, can you just run a pipe with the pressure nipple without the big ugly muffler? Any help would be great.

yes. they make flex cable tap in a nipple and run it anywere you want. Acually I recommend gett the flex cable and use the stock muffler run out the bottom. Deppending on the mounting direction most of the time I get away with just an exuast deflector poking out thr bottom