It has been said that change is good...
Well, changes to the WBX are good for more power...

change the cam and gain about 10 HP,
Change the muffler and gain a few more 2 or 3
change the air filter 1 or 2
Add light weight roller tip ratio rockers and stronger push rods adds @ 10
Change to quad tip plugs adds
You can change only the compression and increase power by 22 HP
Eliminating crank flexing adds 1 or 2
Balancing rotating parts adds 1
Increasing air flow through heads adds 2 or 3 (probably more...)
Match porting intake and exhaust adds 1 or 2
Ceramic coatings adds 2 or 3 HP (probably more...)
Increasing air flow around valves.
Adding 95 mm pistons will add HP
Increasing stroke

IF the changes are done reasonably and all the systems are kept balanced (if
you increase one area how will it affect other areas...) and you do not drive
like a race car driver (remember their engines only last for 500 miles before
a rebuild and some not that long...) and you have used quality parts and care
during assembly, then it can last long than a stock engine (150,000 miles
Plus..)