I WOUNDN'T GO ANY BIGGER THAN 370 OR 397 KITS BECAUSE I GOT A 370 LONG ROD AND I CAN RUN WITH 5, 7 , OR 10 MILL STROKERS I KNOW SOMEONE WITH A 7 MILL 505 T-REX BANSHEE DRAG PORT WITH 41MM ALCOHOL CARBS AND EVERY THING ELSE AND WE ARE SIDE BY SIDE. I RUN 4.20 OR 4.30 IN 300FT. DIRT DRAG AND I WEIGH 230 POUNDS.