I see so many people knocking these heads its unbelieveable. There casting are very strong and are a great head for additional porting. These head starts off with a strong foundation and there decks are super thick with 2.5 csa. most 421 - 434 like a 2.9 3.0 csa anyway,for a nitrous combo. The problem with most 23 degree cylinder head is not enough port volume for all out racing. The rhs 23 degree people almost in 4.99s range with a larger valve swap and more port volume, paper thin so why wont these casting work. You cant change bad location in most ports but these heads are a great start. If you look at these heads in most nitrous applications you see 5.70-5.50 235cc .
The 245cc will probably knock it down to 5.45-5.40. With additional port work you have the potential to be in the paying field with the rhs heads. Im sure i left out alot of good castings but going fast is about port volume and valve & intake thats were all the e.t is. The 265cc 18 degree heads is more port volume and you will see this volume increase in 14 degree as well. When i see people port most of these heads they almost always pick up. Most porters want you to think to calibrate this and that as long as you follow the rules of the throat percentage, and 45-55 degree seats you will be find considering you know your cross section area for your engine and your rpm range. But we have to give thanks to the head porters for the research and development (nascar) top fuel and other people like Mr. Boggs, Spiencer.