Chuckak

23' Bayliner Trophy Hardtop - Have replaced the V6 with a 270hp magnum V8 and had the Alpha 1 drive rebuilt which included new gear ratio of 1.5. Have experimented with 3 blade Mirage props and 4 blade props and have settled on a 3 blade Mirage 19 pitch. What can I do to this drive to get the top speed up. I am currently getting about 46 mph at 4950. The old V6 would get about 34. I would like to get her into the 50s. The prop center line is well below the keel, is there a shorty version lower unit like I have on my other boat's XR drives? Are there other outdrive changes that would help the performance? What about the exhaust system? I am currently using the stock through the drive exhaust. Any modifications available here?
Is there a significant speed/efficiency gain from through the transom exhaust? (I know - a little over the top on a Bayliner...)
I have posted prop questions in the prop forum.