There are alot of smaller cams that make great power, anyhow u could be right

 

there are tons and tons of trex cars running around with stock heads making high 420+ rwhp even on stock ls1 intakes.. i know one that has headers, ls6 intake, stock tb, stock pulley and a 12-bolt with 4.10's thats making over 440 with bone stock heads, i would deffinatly check something other then the intake... you should be making in the 450 range atleast on your stock intake with those heads....i know you have valve relief pistons but i would check to see if you have some bent valves... something is not right without a doubt..

 

yea it's a stock 10 bolt with a 4.10

 

I just had the motor apart and put the pistons in. The heads are brand spankin new and I had it dyno tuned by Speed Inc. 2 days after it was complete. I do need bigger injectors but that's not gonna make up for the power i should be seeing. I had really bad blowby on cyl. 5 before the rebuild and it put down 375hp to the wheels, and now I fixed that and added heads and I only gained 27 hp? I'm stumped.