Or maybe get the Mazdaspeed CAI from the dealer or a third party vendor. It's simply a rebranded AEM, but as rebranded with Mazda logo, it is an OEM Mazda option and will not void warranty. Put on a catless test pipe (you can switch back to stock catted midpipe in less than 30 minutes), and do a simple Hypertech tune. You can switch it back to stock in 5 minutes. My guess is that with those three mods you'll easily drop a full second off of your 0-100 mph times, and can be dealer friendly in a flash (pardon the pun) if you need to be.
But, yeah, a dp is a warranty killer. Even simple SRI's and aftermarket bov's or bpv's (not necessary anyway), have voided warranties. With any mod except official Mazda parts there is the risk of losing the warranty.
With so many things in life, if you can't afford to pay, then you shouldn't play.