I have EMI Thunder Exhaust (came with the boat)
My current riser is a standard riser and ends about where the first weld is on the picture. My current setup is under the swim platform, So the question is If I change to a longer riser like this, proably 8-12 inches longer is it worth the money?
Or have a roller cam(RMBUILDER) using the existing setup?
I just wanted some opinions before I call Bob..

I run a Crane 731 cam with EMI Thunders and the cast riser (short). It gave me a bit of trouble with reversion so I extended the inner with a sleeve. My thoughts are that anything that seeks to put more distance between where the exhaust mixes and the cylinders is a good thing, hence why dry exhausts are the best thing to combat reversion.
I can't see any issues with that set up. Where does the exhaust mix? Right at the end on the downward part?
To be sure you won't have a problem, call Bob and ask him about your set up and get his thoughts, but I don't think you'll have an issue with risers like that.

From where you started (with a cam that didn't cause reversion) you can add 1* duration for every 1" you move the water down stream, you'll know if you got it wrong.

I had a RMBUILDER Roller simmilar to the Crane 731 in my previous build. That's why I wanted to get anyone with personal knowledge. If I am only going to gain 15-30 with a longer duration, I don't know if I want to spend $1,350 X 2 for both engines for risers.
I don't want to guess, like stated in the previous post.

I just thought I could get some good opinions before making the call to Busy Bob..