How are you gonna cut grass when you're running across the yard doing a wheelie?

My opinion is keep it tuned up and it will have more than enough power to cut grass...which is what I assume you bought it for.

I'm thinking you got on the wrong forum for your interests (in higher power output and modifications). Do you know how to do a google search or a yahoo search? Go to google or yahoo and type in "Lawn mower racing forums". You should get a few options to peruse and browse.

I heard Briggablock makes a nice tunnel ram for them. A two speed powerglide and 9" rearend also. Now if you want to re-engine for some real power get you a Wisconson V4 banger. You molds could be endless on them. O wait somebody already done that to a CUB, look on the tractor shed for that one. One draw back with the extended frame turning radius suffers, but you will have enough power to pull a conbine.

Where are Bob Vila and Tim Allen when you need them?

Another option is to lose weight ; )

This link may give you some ideas but it focuses primarily on old Kohlers.

Tractor Pulling Mods

-Deerslayer