I'm getting mixed signals about wether to pick up one of these hand held tuners or go with custom tune. Are there any books or guides out there that show you how to kick it up a knotch with a hand held tuner?

go to their website, they have a great FORUM, that you can get info

Like this?:
http://diablosport.com/index.php?name=PNphpBB2&file=viewtopic&t=917

you can also get custom tunes made via email specifically for your car using the predator... you'd simply send the CMR tuner some log files, and copies of your tune files... they create you a new custom tune and email it back to you... then you import the custom tune file into the predator, then install it to the car... done.

custom tunes can be made by diablosport CMR tuners (like me) for reasonable costs...

when you're ready to get your predator, PM me and I can point ya to the authorized dealer/reseller that has the best deal going on them right now...