I have the iTSX for iPhone. I love it. As far as tune wise it does exactly the same as the handheld sct. But it is cool to pull out ur phone and say ur tuner is on there and show everyone. You can do live data logging. Have up to ten tunes. You can do the 0-60 and 1/4 mile time. Not that I exactly trust the times it says but is still cool. The app is in color and is cool to check out. Also the app has the possibility of updates in the future where you could possibly have more options of things to customize. The iTSX is small and can stay plugged in at all times. You don't even notice it. I'm pretty satisfied with the iTSX. The only problem and I see everyone has it. Not sure why they haven't released an update of some sort for it. But when you are on the gauges part of the app, it causes the gauges in ur car to jump up and down. Doesn't affect how the motor runs and the gauges on ur phone are still accurate. I drove around with the gauges jumping and nothing happens. Drives perfectly fine. Not sure what's up with that. I've talked to a few other people about it and no one can really get a solid reply from SCT or am about what is going on or how to fix it. But that part of the app is rarely used. All the other features work like sex!! Sooo I say spend the extra $100 for iTSX.
Engine/Drivetrain: SCT iTSX with BAMA 91 Race Tune, Airaid CAI, JBA O/R H-Pipe, SLP Power-Flo Catback, Exedy Stage 2 Clutch, Exedy Lightweight Flywheel
Suspension: H&R SuperSport Springs, KYB Shocks & Struts