The 12 valve's are easy to get horsepower from. So are the rest. As I see it all the them take money to do it right. You can get alot of fuel cheap on all the cummins, but then you need more air and then a drivetrain upgrade.
If you are going to do it figure out what you want and do it once. Don't lie to yourself and say I only want 300 horsepower cause most people won't quit at that.
I started with 70 horse injectors and an ez with a hybrid turbo. I really thought that was all I wanted. Now I have adrenaline and 125 horse injectors soon to be 200, and twin turbos. Trainsmission upgrades, whether it be a good clutch or convertor are the best place to start. It sucks building decent horsepower and blowing threw the convertor or clutch. Gauges, a programmer with gauges built in seperate ones.
Turbocharger, hardest on to decide on. I like one that spools quick, thats the main reason I ended up with twins. It still doesn't spool as quick as I would like but I'm comparing spoolup to a hy35.
If you can find people to give you rides in different trucks you might find the combo you are looking for. You will get alot of different opinions on these sights so don't decide real fast. One persons perfect combo might be anothers most hated combo.
My opinion, for what its worth, stay under 500 horsepower and you can live with a smaller turbo that lights faster and a more driveable truck. Watching the pyrometer all the time stinks. It's better to have extra air and not enough fuel.
Good luck.

 

go with a duramax with allison tranny... dodge trannys suck.... im running a dodge with bullydog crazy larry tune and im in my 2nd tranny

 

get a dodge and put a allison tranny in

 

Get a Dodge and put a built 48RE into it.......nothing special about the Allison except the name. Cheapest and best mods I have done are the vent kit and putting 80 PSI into the tires.

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And you think a stock Allison would handle that for much time? Hope you got a built tranny the second time.....mine would have no trouble with that HP.

 

i have a 91 and 08 cummins. i towed with the 91 for years with all kinds of trailers. all i done to it is turn the pump up on it and put exhaust brake on it tq is great. its not fast taking off but pulls good on hills. 5speed stick. of course 08 runs better with juice and deletes but ol 12 has nothing to be ashamed off.

 

The two cheapest mods you can make are big exhaust and a better air intake system. Still going to run $3-500 depending on how you rig it up, and how much DIY you do. Beyond that, if you get a second generation Dodge, there are a multitude of things you can do, from a 65hp chip, to the sky. None of the mods are cheap. I have to agree with the others on this post, if you increase HP you MUST HAVE guages. You can get your engine redline hot just cruising around town showing off a little, and burn up things like pistons...., ruin turbo seals, which leads to blown turbos, which leads to pieces of metal flying around in the engine, scoring piston walls, yuck!

So it a nutshell: Get her where she can breath, slap on as many guages as you can afford (start with pyro and boost) and have fun!

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X2 - I have that exact situation, I watch my pyro like a hawk, and I have stock sticks. Next mod is a different turbo.