Can I take weight out of an NsixOneTour 90 Handle?

I bought the racquet witha (4 3/8) size handle instead of (4 1/2) just in case because he said I could go up but not down. What he didn't tell me though is that going up with a heat shrink adds significant weight to the handle (at least 15 grams).

Now I know I'm really a (4 1/2), so he put a sleeve on it and given the racquet is already one of the heaviest and most head light, it's now way too heavy (370grams+) and too head light (11pts). (I'd prefer say 360grams and 7pts head light).

It's weights are -
Unstrung with No Grip No Sleeve: 340g 12pts HeadLight
Strung with No Grip No Sleeve: 352g 5pts HeadLight?
Strung with One Under Grip No Sleeve: 360g 7pts HeadLight?
Strung with One Under Grip One Sleeve: 370g+ 11pts HeadLight?

Maybe tape on the handle instead of the heat shrink sleeve would be lighter?
If I open the butt cap is there anything I can take out of the handle?
Can I send it back to wilson to upsize the handle foam?

I wouldn't recommend modifying the racket, if you break it Wilson won't touch it. To increase the grip size without adding weight, get hold of a few Wilson Pro Overgrips and build it up with those - they are light, durable and work a treat for the juniors I coach who wish to keep the racket they have developed with but need to increase grip without too much weight.