Nothing for more power in a cdi. Maybe a tiny increase but the contra spring/rollers are the only help there without increasing the HP of the engine.
The issue is the relatively low hp of the engine. Gearing is the key to maintaining rpm/speed. You need to keep the torsion drive closed, and the Var open to keep lower gearing. Light rollers, and a stiffer spring do that. Didn't you install a contra spring? If you did, and it's still loosing speed up hill try the next spring stiffer. Not all springs are the same.