Congratulation on the first flight. especially within the Washington DC area.
I would have to agree that 425 is a bit high. I for one like CHT's below 380 in the climb.
After take off and at a safe altitude when you start your power reduction for a climb as was mentioned got to 5 square or 25 in MP and 2500 rpm for extended climbs. and climb at 110 to 120mph indicated.
I had a constant heat problem and could not climb out with less that 400 until I installed an Anti Splat cowl flap... I only installed one and now my temps are well below 400 on climb out
As far as the heavy wing... make sure that they are rigged correctly...
Ailerons in line with tip on both sides and flaps aligned with the ailerons. sounds simple but if you go to airports and see RV's... some line up but a lot don't.
Make sure you allowed for you as the pilot only. even fuel and a heavy pilot will produce a slightly heavy wing.
Hope this helps.
Smilin' Jack & Anita Hunt
N507H RV7, KJZP Jasper, GA
Retired Corporate Pilot CFI-AI, MEL
CE500, LRJT, HS25, C650, SBJT, CL60
Hunt Aviation, LLC.
Pilot Service, IPC's Biennials.