I have had great luck with my 1988 28ft Excel. But as Paul mentioned the boat did take a lot of work. It was worth it! I think I lucked out when I got mine, the hull was fairly straight with very sharp edges on the transom and strakes. I have next to no stress cracks and I run the boat in choppy water all of the time. I did thru bolt the deck to the hull and added additional stringers in the engine compartment from the transom to the firewall between the larger main stringers as well as cross bracing. I felt the boat was pretty well built but I run a 550hp 502 and I do run it in rough water so I felt it would be good insurance to add the stringers.
I think because the hull I have is so good is the reason that I haven't had as much trouble making the boat run. I get a solid 75+mph on gps with 2 people in the boat and over a 1/2 tank fuel, running in the salt water with a little chop. The boat is stable and predictable and it flys nice.
I also redid a lot of the cockpit, new rear bench to dived 3 person bench and installed solid bases for the front seats as well.
I did away with stainless steele grills that were on the sides of the engine compartment and fabricated some real nice vents out of Corian. Filled the old holes and painted that whol area. I also added a scoop on the engine hatch. It's my little hot rod!!