Is it true you can just use this to tune your car, even if you have big mods??
is it worth the 350?

 

Not worth it. For 200 you can burn your own proms. The extra 150 you saved can cover the time you spend learning. Learning to burn proms can be almost invaluable since every car now days is rolling out with EFI. 200 can program lots of cars, while $350 is only for that specific model/year with that engine.