What mileage on your pickup did you start modding. I just got my 2000 SD Powerstroke and the truck has 144k on it. Runs awesome and no problems have come to mind. Is it to late on this truck
I had about 7 miles on mine when I put new tires on it. I think I did wait for a few years before I purchased my first chip. I think it was in 98' when I got a USGear chip.
I say go for it if its what you want to do. If it runs well then dont be afraid of modding it. If you had 150K on it and some underlying issues, I would pay attention to the issues then proceed to modding.