any idea what speed a 1997 35ss with 502 mag mpi's
would run and the difference in hull between this and the newer 358?

A 1996 35SS w/454 MagMPI's tops out at 67 gps with 3 blades. You would probably see 69-70 with 502's.

The boat GO4BROKE is referring to is mine (it's actually a '95) and it ran 67.1 on GPS with the 3 blades in fresh water. Last weekend it ran 66.7 on GPS with 4 blades. Let me know if you have any more questions.

We were shopping for a 358 last spring and looked at a lot of these used models and toured the factory when down to Miami for the boat show. From what we experienced, the 358 which was an 8400lb boat with 502's would run WOT 69. The new models, I'm told will be less weight, but still a nonstep hull. They also changed the notched transom. We were waiting to hear the new weights on the boat, still no numbers. We only tow and are in hilly country, so weight was a big concern. Really shop around, you would be amazed at how much difference in price you can find. Just have to do a lot of searching. More so on a new to year old model that someone bought and has to get rid of quickly, you can really do well. The Sonic people are FABULOUS!!! We still haven't moved up yet, trying to move our boat this winter and get a garage up for a bigger rig...... Sonics are still in our scope!!!