Best power boosters
 

I have a 04 gt 5 speed and want more power. What add ons should I do and what order. I want to do it in the order that makes the best gains.

The easiest way to get a good seat of the pants increase is to add a supercharger. Keep the boost fairly low (5-6#) on the stock engine. As you add better parts (bigger MAF, throttlebody, injectors, etc...), you can up the boost a bit, but don't go much past 9-10#s of boost on the stock bottom end.
You can also go the nitrous route, its cheaper on the original cash outlay, but you have to re-fill the bottle(s) once in a while.
Then there are turbos. They work great, but take up alot of room. I think next time I build another car it will be a turbo.
Whatever you decide, get a kit designed for your car, it will make installation alot easier.

What is the limit on a stock 4.6 bottem end as far as horepower before I have to open it up. I was thinking about a keene bell and the rest just bolt on stuff.

I can't say for sure but I've heard 9-10# like LX5liter said. MM&FF dynoed an '02 4.6 w/ cat-back exhaust (baseline was 247hp/292tq) and 6,9,11, & 15# from a KB (latter 3 were intercooled and had a chip) as well as 36# injectors, boost-a-pump from the KB kit. There was a peak hp/tq of 351/366, 399/427, 430/466 (w/90mm MAF, 75mm TB, boost pipe +6hp at 6, +19 at 9, +26 at 11). Those mods plus race gas at 15# was 504/521. I wouldn't risk going above 9# but they showed what it's capable of. I'm liking the 4.6 more and more.

hey stanggt95 do you need to increase the rear end axel with out that power? what hp will it hold?

I haven't heard how much they withstand or when's a good time to go to a 9" rear end. The only upgrades that I've heard on the 8.8 was lower gears and 31-spline axles. I'd say w/ that kind of horse, 31's probably wouldn't hurt to have.

In my opinion, anything with 250+ horsepower should get larger axles. The 28 spline stockers may last for a while, but they will break.