My 53 reg td4. clutch has started to slip slightly on steeper up hills just when the power come in. its got a synergy box fitted and has been decated as well so wondering if its struggling to coupe with extra power. Are there any options out there with out going the route of a full on race/rally paddle style, which would be OTT and impractical for every day use.

Probably find the DM flywheel is failing when you change clutch you can if you wish go SM with a conversion kit.

A standard new one should be more than man enough for the job unless you are constantly towing heavy trailers up hills or off-road. I don't think anyone round here has found the need for a hd clutch with a synergy.

I think winu fitted an oe had clutch to his L series. But he likes spending money........

You have the choice of single mass flywheel conversion or to stick to the original spec dual mass. Personally i would replace with standard clutch and dmf unless you are expecting to wear the clutch out again!