Okay before I start I’m gonna say I understand something’s that work on street cars might not work on pulling trucks but you still need to stay in the efficiency range. I just got back from a car show and this guy was telling me about this engine his dad built the used 230cc dart iron eagle platinum heads with the 49 cc chamber and he claims to have ported them to 250cc (I don't think you could get that much) so I asked how many rpm’s are you running when he said 7000 I said well you cams either to small or something’s wrong what size engine are you running he said 355 I was like WHAT!!! THAT’S TO FUCKING SMALL FOR THE HEADS OUT OF THE BOX!!! The 230 head will support 7000+ on a 400-inch motor even better on a 350 and you've ported them to 250?? You destroyed the heads go look for someone with a 434 and see if they'll buy them. I tried to challenge him to a slip race told him to swap the engine from the truck to your dads 70 nova and race my 400 with 215 cc heads and he just wanted to change the states and cry and everything else he said I’ll race you with the 283 that’s in the car now I was like no I wanna race the 355 with the 250cc heads you got 35cc bigger heads then me if bigger’s better you should blow my doors off. I even told him if I bought those heads and put them on my motor I’d probably run slower.