Power difference before and after Maintenance?

[+SHO-]

OK, Ive heard over and over that Valve adjustment is critical on these yamaha engines. and im sure its true. Ive owned a few SHO's over the years and have never owned one that had the service done to my knowledge. luckily Ive never had a problem. Now I have a 95 ATX and plan on running it for a while so its time to take care of buisness. My car has 128K and I dont know if any maintence has ever been done. The engine runs quiet and smooth. But since it has oil leaks I am dropping the entire engine out, replacing all external seals and gaskets, all major sensors, timing belt, waterpump, and installing a new set of larger cams with valve adjustment. Im sure the new cams will yield more power with supporting mods, but how much power can you get just from proper valve adjustment? I admit my car seems slower than the last one I owned and im told power can drop off over time. Has anyone felt a difference after a full maintenance?
any info much appreciated...

 

[projectSHO89]

but how much power can you get just from proper valve adjustment?

You will only recover whatever may have been lost, if any.

Steve

 

[RStalveyARFF]

what you'll notice is a smoother, more responsive engine.