Don't know how much if any.
Boat was bought from Checkmate in 85 by my Buddies brother who is a doctor. The same model never came with a 383 so no numbers +/-.
I've been in it and speed-o does not keep up and it doesn't have a GPS. Pics of it on the water with 4 people in it, all you see a WOT is maybe 2 inches in the water. It did not chine walk with me and Buddy says it is touchy but pretty stable
Buddy also spent 5K 10 years ago and installed a killer stereo system. It can get loud but it just has some of the best sound I've heard on the water and not even getting loud.
Buddy has a need for speed, he even modified his Seadoo and that thing is scary fast. I drove it WOT and dam I had to back off before it reach max