Straight exhaust

DO NOT BEAT ME ABOUT THE HEAD FOR THIS ISSUE, PLEASE.
Having built many race engines, I understand the advantage of straight exhaust for horsepower and other considerations.
Does anyone have an idea why a straight exhaust on the Rotax would not be an advantage. Say a two into one dual exhaust.
Almost all smaller aircraft engines run straight.
Less heat in the engine compartment?
Less weight?
Engine breathes better?
Runs cooler?
Gets the oil cooler away from the exhaust collector?
BTW - I have done this a number of times to smaller 75 and 85 continental engines for improved results. It is not difficult to fabricate exhaust systems.
(I have not talked to Rotax about this!)

Dick
RV12 N912RJ
FOR SALE
'46 Ercoupe (Completely restored) STC'd LSA

Dick,

The reason for the current design might be to meet the European noise regulations, which, as I understand it are very restrictive.

It could also be for backpressure issues as some engines actually produce better power with a little back pressure. I really don?t know.

More horsepower is always better

Dick,
If you think that you can get a few more horses and still run cool, go for it!! It looks like you have a test unit for evaluating the benefits. If it works, you'll have a lot of followers. If not, you just wasted some of your time. An additional 10hp would be terrific! As noisy as the RV-12 is in the cockpit, a few more DBs outside won't matter.
Good luck
Tom