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need PA 12 exhaust advice


Registered User
My PA-12 was originally a 100hp then upgraded to 150hp via Mckenzie STC using the same exhaust.

Is the stock 100hp exhaust acceptable for a 150hp ? If not, does anyone know if there is a muffler only replacement that works with the current manifold pipes ? or do I need a whole system ? I think the STC allows a PA-18 exhaust. Would there be a difference in peformance between the old 12 exhaust and a PA-18-150 exhaust ?

I had a lot of people tell me that your O320 won't make 150hp with the old straight -12 pipes. On the other hand, also I had people tell me they would rather have the old pipes because of the cracking problems on the crossover pipes.
They will fit on the O-320 with the stock -12 muffler (in fact fit easier than the crossover style pipes), except for possibly needing about 1/4" added to each pipe where it enters the muffler as the O-320 seems to be slightly wider. The MacKinzie STC was the only one I could find that reused the original pipes.