Today's Tuners

it all depends. What vehicle you are trying to put it on, what you are looking for. Tuners by themselves are not a good idea. 1st is a better air intake, 2d a better exhaust system to let the engine work its best. Tuners generally add more fuel to let the engine develop more hp so it is a wash on better milage. Tuners can add some good aspects but will possibly bring out shortcomings that are in the system. Get some copies of the better magazines, diesel power, diesel world, if a cummins get diesel tech. They will give ya some ideas on what are available plus they have lots of ads to sort through. I run a hypertech economiser on my truck, supposedly gives 30 hp 50 lbft of torque? It hasnt hurt milage and even with it on I pass my emmisions tests with only 1% of particulates. I also run a 4 inch turbo back exhaust with stock air cleaner.