I was just wondering if anyone (or the fabricators on here) can tell me how much of a difference is there in the downpipe position between the two different motors, assuming the manifold is the same. I was just wondering if I could possibly use a H-series downpipe on an LS motor.

 

I just got done making a custom 3"dp for a LS last week. Prelude's have front crossmembers which make it very difficult to fit in a downpipe, so the downpipes typically run really close to the block. To be honest with you, I doubt it is going to fit. It all depends on the manifold as well.