I am looking at a couple used boats and have basically narrowed it down to two. One is a great condition 521VX and one is a good conditon Z21. Both are very close in price. The 521 has about 150 hrs on a 250 HPDI and the Z21 has 240hrs on a 250 Pro XS. I haven't had either of these boats so im looking for feedback as to the best option. Neither has any engine warranty so that is no a factor. What kind of speed could I expect out of each of them?