LOL Amazon. It's a great website for a lot of things, modifying cars is not one of them.
The XCAL is going to be your biggest "bang for your buck" of any single mod and it's also either necessary or highly recommended for most other mods, for example you don't NEED a tuner if you decide to add downpipes but they tune can be adjusted to take full advantage of them if you have one. Other mods like the 3 bar MAP or meth injection are going to need custom tuning.
If you're interested in saving a few bucks, I have an XCAL 3 that I have just laying around because I upgraded to an XCAL 4 because I like shiny things and sometimes have more money than brains (what I'm getting at is there's no performance advantages to one or the other) that I would be happy to sell you at a very reasonable price and you could purchase just the tune files from Torrie, the "man behind the curtain" at Unleashed. Torrie responds extremely quickly to emails and has always been great to deal with in my experience, and he will update your tunes as needed as you continue to modify your vehicle, at no cost to you.
