4.0 to 5.0
 

So after having a 4.0 4x4 with 205 hp, it's a lot better than my 150 hp Mazda. I'm fairly inexperienced with anything mechanical but came to take a liking to diesel and v8's, pretty much anything with nice sound. I do know that transmission problems would normally occur for a 2.9 cyl, but what about the 4.0? I was looking to maybe soup the engine to about ~400hp, but again with the trans. Does anyone have any idea what kind of mess I would be getting into?

Automatics are, of course, stronger than manual for this

5R55E automatic can/should take 350-400HP as is, assuming its in good condition, thats the stock 4.0l SOHC transmission

M5OD-R1 might be OK to 350HP , but T5 would be the better choice above 300HP