Dean's Tansom Mod worth it?

[need4pwr]

I have the transom off for resealing. Is it worth the mod? What are the gains?

2017 GP1800

Dean's Team SVHO Transom Plate Modification Service The Dean's Team Transom Plate Modification (for Yamaha GP1800 & FX SVHO WaveRunners) is now available! Reduce cavitation and increase the water...

DT Transom Plate mod service

$149.00

[FXSlowKroozer]

Typically with that type of modification you lose speed because your letting more water into the pump.I dont have a number for you on exactly how much because I dont have a GP but its always a give and take with the holeshot stuff

[K447]

Typically with that type of modification you lose speed because your letting more water into the pump.I dont have a number for you on exactly how much because I dont have a GP but its always a give and take with the holeshot stuff

The transom plate modification simply changes the transom plate 155mm outlet diameter from a 2.5mm right angle step change right in front of the impeller (thereby creating a localized turbulence in the water flow) to a 'tapered' diameter change to properly match the 160mm intake diameter of the jet pump itself.

The 155mm inlet diameter on the transom plate remains unchanged.

Why would you think the transom plate modification on GP1800 would negatively affect acceleration from low speed?

Reduced cavitation and stronger acceleration is the original reason for doing the modification.

[SpeedJunky]

I tapered my transom plate using a flapper wheel. I did notice a improvement.
Seal the transom and the intake grate also.

[need4pwr]

I tapered my transom plate using a flapper wheel. I did notice a improvement.
Seal the transom and the intake grate also.

Which wheel did you use?

[TAB686]

On my 11 fx i went to the 160mm ring and used a file and the 2" flap wheel and other sand paper to get it matched..the transom photo was not a final fitment but it does look like the stator. I also did the stater to match just to maximize flow(before amd after in one shot.

[SpeedJunky]

Which wheel did you use?

I believe that wheel is 120 grit. I also hand sanded it with some 220 grit and then polished it with some of these:

[yellow jacket]

i have the dean's transom mod can't say if I lost any speed with it, i never ran the ski with out it but she pulls like a SOB from a 5-10 mph kick...