Love the Sam James! Love the look!
N23J,
I have a Sam James on both my flying -6 and on my -4 Fastback I'm building. I have 1,000 hours on my -6 with both plenum and cowl and no problems noted, flying out of 'hot' TX, NM and AZ with no unmanageable heat issues. Fly all recreational aerobatics and think, besides any promised speed gains, the look is very, very nice, in my opinion.
My -4 will not have the plenum.... My father in law finished his Super -8 without the plenum and is also not having cooling issues so wanted to avoid the hassle this time of the plenum. We'll see. Sam James thinks I will lose some speed without it...
I agree with the previous poster concerning aerobatics in the RV series. If someone is concerned about the 'limits' a prop extension puts on their RV, they may be interested in looking at a more aerobatic capable steed. I personally own a YAK 50 for body punishing feats and relegate my RVs to gentleman acro, rarely exceeding 3-4 Gs in all maneuvers. Do I feel i can't do 6 g's if needed? No, but can really not see a need, in MY situation.
BTW, love the N#. I tried to get that one as well as some others but finally settled on N234JJ, got the 23 and J in there at least!