I gained 61rwhp from a cam alone…
if you only gained 40rwhp from a intake/full exhaust, cam and dyno tune with stock 243 heads, you have yourself a MAJOR turd!
with the right combo from mods I listed above…you should have no problem seeing 420rwhp…
in most cases, a intake,full exhaust, cam and dyno tune nets around 70-80 rwhp gain over stock on ls1/ls6’s.