Cams and gears
 

I have a 2000 mustang gt. I have an intake, shorty headers, exhaust and a diablo chip. I was thinking about putting stage 2 cams and 4.10 gears and wondered how much hp/tq gains I will get and how fast my 1/4 will be as well thanks.

First, get rid of the chip. The car is OBDII, so chips are somewhat pointless. Instead, get a handheld tuner (this way you can continuously update the engine tune vs. constantly replacing chips). Now, stage 2 cams is kind of a ricer term. What cams were you looking at? Comp? Crower? Another brand? Now, to find out the gains, figure out what grind you want and do a google search for it (you'll find dyno numbers). From what most cams that are considered "stage 2," torque stays relatively the same, but power will go up 10-20 hp, depending how far the torque curve is shifted and your head flow (I assume stock heads). Cams are very system dependent. That is, you select it based on what you have. As such, what are your goals? Do you plan on porting the heads/getting new heads? With the stock heads, and stock intake manifold, there really isn't much point to go beyond a "stage 1" cam. You'll just be spinning the engine higher while making only marginal gains and loosing it down low. If you don't plan on doing anything else that'll improve the breathing, I'd lower it down to something that'll work better (unless you just want the sound, then go grab a "stage 2" cam of your choice). As for the gears, I'm a fan of my 3.73s, as the 4:10s kill your mileage and make 1st gear completely useless, but plenty vouch for the 4:10s.

well the tuner is like a heldheld one you can constantly change the tunes. I was looking at some comp II cams looking at porting the heads. As for the gears go I just want to improve the 1/4 mile time which ones would work better? Pretty much the goal for my Gt is to run 13's on the track.

A stock GT should hit high 13s so you don't need to go nuts. If you're getting ported heads, I would still stick with a "stage 1" cam unless you bump up the compression ratio. No need to run excessive gearing or excessive cam if it isn't needed. With the improved head flow, and slightly longer duration/lift, power will go up nicely. Add in some mild gears (3.55 or 3.73) and your time will improve a good bit, without any noticeable sacrifice in idle or below 2000 rpm power. Sure you can run larger cams and lower gears to try for better times but then you start to loose grunt down low. But, you can also call Comp, as they will give you a recommendation for the best cam for your application. I just don't see a reason to go nuts to have good 13's times unless you start talking about upping compression.