c15 at 525 setting is still weak to me. help please

I finally got the truck ive wanted a flat top 04 pete 379 with a c15 and they set it to a max of 525hp at kennworth. mbn08433 is the serial number. I want this thing to be STOUT. I really hope i have not bought the wrong engine. I want 800 hp to the tires eventually. I need to know what to upgrade a little at a time. ANY upgrades for power that you guys know of is great. this is how my truck is sitting right now. 525hp setting on c15 single turbo. Motor is clean with almost undetectible blow by. dual breathers. dual exhaust with mufflers(factory) 690k miles. fro???10c trans. 355 rears with pete flex air.

 

thanks yall i will check it out

 

Ok i read the mbn thread lots of information for me to absorb.. I have a few questions. first i think i need to get rid of the mufflers/converters or whatever they are. Ive always had straights on every truck ive had but I don't have the money yet to put those "picketts" on. I thought about just putting in a straight pipe but will have to fab brackets and clamps and don't want to do all that. my quesiton is what kind of mufflers do you guys recommend. straight through and cheap will be best lol. then I want to upgrade in phases. don't won't to go in to the motor yet...but eventually will. any suggestions.

 

I have noticed in tenth gear on a long hard pull the boost gauge says 37psi. then the check engine light will come on for a few seconds.. I hate that. anyway where or whois the best place to flash the ecm