final purchased my first cummins it a 98.5 24 valve auto 4x4 . my truck is completly stock now i am looking for info and advice as to whate upgrades would be good to pull 20 or higher mpgs and also the best tunner for better fuel economy

Do you know what your mileage is now? If you put a Bhaf (air filter) and 4"exhaust that will make big dif. right there.Check out my mods. but rember I weigh 8900lbs and getting 16 in town and 18 hwy and all kinds of wind drag. When fuelmileage was checked I didnt know at the time that inj. where low pop pressure and nossels werent in good shape. Michael if you are reading this these are the ijn. that I was sending you all had low pop pressure and 3 nossels where not to his liking.These inj. only had about 45k on them that is acording to Sean that is who I bought them from.

To reliably see 20mpg highway, you need to drive about 65mph or less, keep boost under 5psi, and EGT's under about 600*. That's with stock sized tires. With your 98.5, the first thing I would do would be to get a set of gauges......EGT, boost, fuel pressure, and tranny temp for your auto. Then, I'd look into an aftermarket lift pump that will reliably keep your VP44 in fuel!!! The cheapo way for an intake is to "gut" the intake tube of the baffles on the inside and then to "swiss cheese" the bottom of the airbox. Don't cost anything except time and you'll get much better air flow. On my '99 I cut out the resonator and the muffler and ran a straight pipe. It's real loud!! Once you get all this done, then I'd consider a tuner or something. Gauges first though, so you have a "baseline" to start from with the rest of your mods!!

thx guys good info im looking into an airdog 150 , 5inch exhaust .afe stage 1 intake three a piller gauges maybe power puck or edge ez havnt decided yet , i dont no what im getting foe mpgs right no just got the truck and waiting for weather to brake before i put on the road -20 right now in upstate NY

The week link is the tranny.If you add a box/programmer remember,it only takes about 120hp more to kill it.If you try.Because when hp is added so is torque.Egde is a good box.Just go easy on it.If you start to get the hp bug and get a built tranny get a billet input and intermediate shaft.Stay away from billit output shaft.Them can be changed with the tranny in the the truck.Also needed is a laminated flexplate.Again i would stay away from a billit flexplate.They dont flex and you can hurt the crankshaft.Suncoast has a good lam. flexplate.