Its better to get a custom tune from a local shop. If you cant do that then Id go to Tim @ Modular Power House. He dose alot of blower tunes but Im sure he could send you something for your car. Hes one of the best around but you still need to take it to a dyno to make sure the A:F is good.
If it's basically stock and you are adding a wet kit, a mail order Xcalibrator 2 handheld would work fine. If you had access to a dyno or had a wideband, it'd be even better to dial in the AFR. The wet kit mfgs go really conservative in their jet recommendations, so it'll be on the rich side. Some SCT dealers (like us) will offer free emailed tunes after you buy one and send in datalogs. You can usually dial it in really well. They hold 3 programs - you could do one for NA and two nitrous tunes. With any wet kit on a returnless car, it's always a good idea to get a kit that offers a fuel rail accumulator so the rails doesn't get sucked down and cause a momentary lean spike.
If you need any info email me at don@lasotaracing.com - I'm on here all the time.