anyone know speeds of 38 slingshots with 502's and 500's .

500's should run 87 MPH

I have a friend with an 02 344 with 500's, motors aren't broken in yet and I have seen 93 on GPS. I expect a 388 should do very close to the same speed. The boat my friend has was used by Powerboat Mag as part of the 2003 performance trials, which should be coming out very soon. Hope this helps.

600's ran 94