Not sure how relevant it is but when I first got the truck in 2015 just for fun I took it to the track and it ran 15.4's , I ran it again this past fall and it was running similar times, so it didn't lose any power.
I didn't buy the truck to race and I really don't get on to much, but I have a 69 Chevelle and frequent the track with it "the chevelle" often .