this winter I plan on rebuilding my 305 up to handle N20. How much do you think it will cost to rebuild the engine to handle a 75-100 N2O mixture with the fuel? Also like all the small things, pistons, cam, ported heads, etc.? How much for a total do you think?

and are there any "secret" or non-visible nitrous kits that can't be seen when openin the hood?