Is it possable to install a performance (racing cam shaft) in my
98 f150 supercab 4x4 with 90k+ miles? will is work or just a waist of time and money? will it mess up the computer?

already installed is the hypertech programmer and single 3" exhaust all the way, with a V-force muffler.

 

Yes, you can install one. I can't give you numbers on how big of a difference it'll make. For the computer you will need to have the truck dyno'ed tuned to get proper Air/Fuel ratios for your vehicle.

Also, you have a 98 truck so you don't have PI heads unless you put them on yourself. They're around $1800 assembled for the pair and will give you a nice horsepower increase if you keep the cams they come with. You could also put new cams in those heads before you have them put on and can expect a real nice HP increae. You're looking at a lot of $ though.

Have you thought about doing some other bolt-ons first? I put Underdrive Pulleys, and Troyer Electric Fans on my truck and they made a nice increase. Certainly not as much as cams and heads but not as expensive.