Is anyone using them i know the cnc'd arent much more but i got a good deal on stock heads so i plan to put patriot gold springs on them have good valve job done and mill them to 65cc chambers. will i really be leaving that much on the table in a 408. I seen most graphs show a 20-25 gain over stock but thats on a 416 and an engine dyno.

 

You'll be fine with a valve job, and mabe a little help in the exhaust. It seems fully ported l92s only net you 10rwhp.

 

I think the will work great for you. But dont listen to me, people say that with my 408 L92/L76 setup all I can muster is a 11.80 1/4 mile pass and thats not enough? Lets see I weigh 4500lbs put my engine in a F-body and it should run a high 10 sec pass? Still not good enough tell to kiss our #&%!!!!