[Mike Carr]

To the best of my knowledge, no they don't. I believe they follow the NHRA classification and HP, with some exceptions. For example, the '93-'98 LT-1 is rated 279 in NHRA S/S, and still at 275 in IHRA. IHRA allows pre-1960 cars in Stock, NHRA does not. IHRA also has some different classes not offered in NHRA (Crate Motor Stock, Stock GT, Pure Stock, Super Stock Production, as well as seperate Truck, EFI classes and more FWD Stock classes). Some HP ratings will differ. On the Tech page there, there should be contact info for all the IHRA tech personel, best bet would be to contact someone and get an answer.