it really all depends on your situation.
if you are far away from any reputable dyno tuner, then a handheld is all you can get.
of course you get the best results with a dyno tune, but it all depends on what you already have in the car. things like superchargers, turbos, nitrous, heads/cams really need a dyno tune because they are tedious to tune. if your car is totally stock, or you just have simple bolt-ons, a programmer is just as good, because you can fine tune (not just fan speeds & limiters, but injector slope, power enrichment, disable DOD for the L99) the tune yourself with a diablosport programmer
if you have simple bolt ons like intake headers exhaust, then you would do fine with a programmer.
if money is an issue, you can get a diablosport predator for $325 vs. $600 for the trinity and $400-500 for a dyno tune, which has the same exact tune as the trinity, only difference is the touch screen, drag tree & monitoring functions.
the good thing about the diablo tunes, you can dial in the fueling yourself or contact a reputable CMR tuner (like 06MonteSS) and get a custom tune.
i'm not trying to be pro handhelds, but that is what i have because there are no reputable dyno tuners in my area except for imports.
if you choose to get it dyno tuned, see if they charge for flashing the computer back to stock for warranty work, or if they will do free updates, because chances are down the road your going to add something or need to get something adjusted and will have to go back to the dyno tuner to get that stuff done. i have flashed about 10 different tunes into my computer tweaking it for every drop of HP and also stuff like changing rev limits later on, because 6200 just wasn't cutting it.
April 2010 Member/Car of the Month
Gone but not Forgotten!