Rotax 912 80hp not making peak RPM

hi Guys, 

back again with another 912 issue. Recently did my SAI on my skyfox gazelle, rebuilt both carburetors as well as alot of off schedule inspections so i know the aircraft is up to scratch.

anyways here ill start, first start after carb rebuild we had some fine tuning to do to balance the carbs but had it purring like a kitten soon enough. doing run ups, mag checks all good. done a high speed taxi run to ensure everything was fine just to see im peaking at 5200 rpm, no hesitation through rpm range, transition is smooth and effortless.

got back to the hangar and done some rig checks to ensure that full open and close was being achieved on both carbs and inspected fine. Engine was making power before meddling with it.

engine stats are as below;

TSN - 2160 hours (engine is on condition)

5 year rubber replacement done 2023

Leak downs - 78, 75, 75, 76

running premium unleaded

oil filter was inspected clean

8 new plugs installed

all jetting is the same as original prior to carb refurbishment. diaphragm notches are set into their respective grooves, needle notch is second notch from the upper end (3rd from the pointy end)

any and all assistance would be of great appreciation.