Cams or Gears?

[00stang]

Hello,
I am trying to figure out what mod to do next to my 00 gt convertible with an Auto tranny. with 90,000 miles on it, it runs pretty strong, but not strong enough to leave some (it does spank a lot) of these new cars in the dust. I eventually want to tear the whole car apart and put a built cobra block with twin turbos in it, but until I buy a new house I need a quick fix for speed! So cams or Gears are my question. I am pretty good with working on mustangs ( I own a 66 and 68 coupe with 302s), however, i have no experience with the new mod motors. I have a semi- stupid friend who did his own cam installation and he had a few problems (all because he's stupid), so I am pretty confident in tearing the engine down to put in new cams. Although I have been told gears are the best bang for the buck. I would go with 3.90s, but I was given an estimate for $400 to install them at JPC racing. This seems super expensive for gears, right?

Any one know af any good places to take my car to get the gears installed in the Baltimore, Md area?

Mods: C&L MAF/CAI, and SLP loud mouth x pipe and cat back (super loud!), SCT Xcal 2 programmer with 93 oc tune.