i dont think the aem ems is junk, i would call it....over priced.
just so you know, OP.....if you are content with 400whp or so, a stock sleeved and mild built gsr will be fine for you. its what i built and am building another one for my brother. basically rebuilt gsr bottom, cp 9:1 81.5mm pistons, eagle h beam rods, STOCK sleeves bored .020 over and STOCK head. once i finish my turbo kit, i will get it tuned at around 425-450whp and still be reliable.
check out
www.evans-tuning.com for a bunch of dyno charts so you can see what it takes to get X amount of power