Cap, Tell me alittle about your 426. I have an aluminum block 426, 6M that has a decent amount of cam surge or surging on start out....My 426 is a 4.125 bore x 4.00 stroke, apache heads, the cam is a 113.5 LSA, 231, 236 duration. I made 500 TQ and 508 horse. Arrington tuned it and it was a mess, sent it to Mike at OST dyno and he got rid of 75% of the surge but it is not as easy as a stock 6.1 to drive. I think the LSA on the cam has a lot to do with the surge. Brian