Roush Gears for a '01 S281 S/C?

I understand that I might be able to improve the performance of my Saleen by switching from my stock gears to something else. I don't spend much time at the drags (maybe once every couple of months), but I do visit several semi-local race courses frequently where the average speed is around 90 MPH. Does anyone have any suggestions for gears that might make my car a little more fun to drive in the city and improve my performance on the road course? Also, HOW can I expect my car to perform (top speed, gas mileage, etc.) with some of the gear options (i.e 3.73's, 3.90's, etc.).

Thanks for the suggestions!

~ Billy

2001 S281 SC
5300 ft. above sea-level
Chicance Saleen Supercharger RIPP Kit
Chicane 66mm blower pulley
Max HP 336
Max Torque 350

Thanks for all of the information!! It is greatly appreciated. I am probably going to try the 3:73's.
I understand the tire size stuff. Man! I'm running 295/35/18's on 18x10.5's out back and I still spin up through a good part of 3rd. If I decide to go and have fun for a day, I can burn them right down.

*****
In response to Mstng2/Stallion, I haven't performed any custom programming yet. I want to add a little timing to my car a get a better grip on the A/F mixture, but aside from that, my car is running pretty good power considering my altitute and Eaton M90 blower. See the dyno results attached to this response.
I need to get the car tuned but I'm still kinda' shopping for the right person/company to perform the tune. Though, after speaking with Joe at Chicane I might be use and a guy by the name of Doug at Performance Autosport, Inc. (www.performanceautosport.com). Why? First, Joe over at Chicane is extremely knowledgeable about Saleens. He is the guy I go to when I need to really understand my Saleen and makes some great parts for Saleens (he use to work for Saleen) and he always hits the nail on the head, so to speak. Anyhow, he referred me to Doug over at Performance Autosports, Inc.. So if he recommends him, I feel pretty confident I can get a good tune. They use the SCT software over at PA, so they can actually read my Saleen programming and modify it, rather than reflashing and starting with a totally custom tune.

Hope this helps!

If anyone has any tuning suggestions, I'd really appreciate hearing them

~ Billy
2001 S281 SC
Chicance Saleen Supercharger RIPP Kit
Chicane 66mm blower pulley