As long as there is enough piping to keep atmospheric pressure away from the exhaust ports. That's what would be bad. 14.7 psia is atmospheric pressure. a=absolute That makes for lousy exhaust extraction. :eek:
If you want to think about it from a combustion point of view; look at it from the two parts of the exhaust cycle. the first part being the pressure from combustion being released and the second from the pumping of the piston.
