on a 353 fastec with 502 mpi's twin step currently tapping the limiters with the stock non labbed bravo 1's...what diff would be seen between these 2 props ?

Hydro's will lift the stern more so than a Bravo therefore Bravo I props have less stern lift.

Julie

The Bravo 1 will have better mid range cruising efficiency. They may also put you on plane faster. The hydro's will pull the R's down a little more than the B1's. Depending on the weight and balance of the boat, the Hydro's could have a 1-2 mph top end advantage because of the R's you can turn with the B1's.

Every identical boat is different so back to back testing with good note taking is the best way to getting your answers.