[Aussie Mike]

I'm going down the LS1/LS6 route with my Cobra. These motors are used in our local GM cars and the guys down here are getting huge HP out of them with not a lot of work. On a factory slug version LS1 just adding a set of headers a cold air induction and some carefull tuning of the ECU can yield figures of 330HP at the rear wheels.

The bottom end is emensely strong in stock form and there are many blown combinations here reliably making 500 rear wheel horsepower with a stock crank and rods. There was an article I was reading a while back of a local tuning shop trying to find the limit of the bottom end by feeding the motor more and more Nitrous while running it up on the dyno. It got to nearly 700HP before it burnt a valve. On striping it down, the rotating assembly was perfect.

I bought a new crate motor for AU$6750 (US$4800) and there is no way I could build any kind of Ford motor or older generation Chev motor that has the out of the box potential of this motor for that kind of $$$

As for being hard to modify there are a ton of after market parts available now, rods, cranks, cams, heads, manifolds etc. There are guys down here that are boring and slieving the standard LS1 alloy blocks and dropping in stroker cranks to make 422 cubes and bigger.

Cheers