You are going to need a tuner sooner or later anyway. I picked up an unlocked XCal 2 off eBay for $150. There are tons of tuners floating around out there for sale. Don't spend $375 on a new one. Usually you can get them for $150 - 225. Just make sure you are dealing with someone reputable that will set it back to stock.
You can pick up a used JLT or C&L for pretty cheap, and then get a single tune from Bama for $50 (or 3 for $115). That will wake up the car more than the 3.73's will, and you are gonna need a tuner sooner or later anyway if you are planning mods.