looking to buy my friends 99 chevy 6.5 diesel crew cab long bed will be doing some mild towing so no need to improve that but wanting some better mpg and a lil more power out of it wat can i do to improve it dnt worry bout budget just tell me wat i can do

 

ATT turbo.

 

was think straight pipe bosch HO injectors a air intake gauges and water meth kit

 

do a straight pipe, intake and #9 resistor! i have that done to mine and she seems to tow fine, fuel millage is also alright!