Slit exhaust COX cylinders.

I have 2 slit exhaust cylinders, non-SPI, but 1 booster flute in each of the 2 bypass ports. I think these cylinders are converted to TD049 cylinders by Bernie and Matt, by having the middle bar between the slits removed, and the bottom slit edge lowered to make it SPI.

I  have 2 shortened and lightened pistons bought from Bernie, that will turn the non-SPI slit exhaust cylinders to SPI, and given the lightened piston weight, may add some rpm too. So the cylinder piston combo will have chances to perform like a TD049 combo, except the effect of the narrow, slit exhaust

My question is, does anybody have a reference rpm measurement that will show what impact the slit exhaust, owing to the choked exhaust flow, will have on the performance, compared to a similar, no-SPI but full open exhaust?

I figure that even in a fully-open exhaust cylinder most of the exhaust gases should have left before the bypass port is opened by the piston top, otherwise the charging of the cylinder would be hindered by the cylinder back-pressure. And, in a slit exhaust cylinder, the bottom edge of the top slit maybe level with the top of the bypass port, so I assume the narrow slit exhaust will not obstruct the discharge of exhaust gases?  
All in all, because of the lightened piston skirt I expect equal or better performance than  the TD049 cylinder...maybe wishful thinking...