personally, i wouldn't put nos in. u've got a 454 so use its potential rather than putting in a better fuel mixture that always has to be refilled if your going to use it. get a big cam, good heads, and intake, all with matching rpm. you already got the exhaust and ignition covered. if you don't have the money for all new heads, look at replacing the stock rockers with roller rockers. i'm looking at all the same stuff now for my 350. and am currently getting as much help from ppl off this website as possible. the only way you should go with nos is if you have the upgraded engine and still want more power. or if you are racing it at a strip. but as far as i'm concerned, its better to have the good engine that makes raw power, rather then just injecting it with nos. anyone can do that. but thats just my 2 cents. good luck either way you choose