Well there are couple things in this thread worth being covered, most of it could be done by searching threads.
I guess I scanned specifically for this particular issue, and not looking for pieces here and there. Sorry about that.
it might be worth buying a tuner. This will handle your speed calibration issues etc. There are several ways from buying recalibration tunes and what not but this mod will benefit you as well along with fix the reading of your speed and any other future errors.
When I purchased the car it came with an SCT SF3 Tuner, but I don't see anything in it that would adjust the speedometer? Are you saying, when I do buy a tune that they can adjust the speedometer calibration through the tune or computer modification? I do plan on purchasing a Bama (or similar) Tune once I have everything purchased and installed, but that won't be before spring. If they can reprogram the speedometer with a computer change, that is awesome and question answered. I was under the impression it was mechanical?
4 new tires with new wheels and gears well cost you well over 1000. Just the gears alone will run you to about half that with install costs not even covering the tires/wheel prices.
I'm going a bit on the cheap, as I'm not competing nationally and it's just a hobby/fun thing for the wife and I to do. I "just" replaced the tires on it with some Falken ZIEX ZE-502 for $500.00. Unfortunately, after doing so, I found a crack in one of the Wheels and will have to replace it before next year. So, I was thinking if I could get new wheels and transfer the tires to them and I'd be good for a year.
As for the rear end gears, I'd replace those myself with a replacement kit, shims, gaskets and so forth. So the cost there is about $200.00. With Wheels and Gears, and Gear Kit it would be around $1000.00 total if I can keep the same sized wheels. If not (having to increase size to compensate for speed changes and offset for fender width), then I'd have to buy new rear tires (same brand/model different size) with new RIMs.