Grip Puppies go on pretty easy if you have an air compressor with a narrow tube gun that will fit under the GPs. You have to soak them in VERY soapy water ... get them really wet. Then as you slide them on, just use the air compressor to inflate them a bit and they go on very quickly. Use dish detergent.
If you don't have an air compressor, just soak the crap out of them in VERY soapy water. They will slide on with some twisting over the stock grips.
I've done both on several bikes .... both work. You can trim the GPs after you get them on with a razor knife, or blade.
You'll find them a bit 'twisty' for a couple days until the soap/water dries up. It all turns out fine.
GPs are cheap, EZ on (above notes),