I have an 02 CR125 w/ the V-Force and it helps throttle response, low-end, mid and top. In my application, it hasn't taken anything away at all, just helped out the power delivery. I would get one for your bike. Although the 00-01 will fit, get the 02 because it is made to fit the manifold better. And they are adjustable for low/hi tension. The reed holder plate can either be flipped over, or loosened and allowed to slide up or down to allow the reeds to open sooner or later. Just leave them stock, it is the best for MX. As far as any 125 having bottom, it's not likely you will get a heck of allot of bottom end out of the bike w/o extensive porting and motorwork. Low-end is the hardest thing to get out of a 125. Per some of the reommendations from this site and my own trial and error, my best set up for my 02 at 0-1500 asl was
Stock jetting w/ VP-C12 @ 32:1 synthetic oil
V-force reed assembly
FMF-Fatty w/ Shorty
13/52 gearing, (13/51 stock)
Weisco pro-lite for better response and less noise in the engine
With these mods, you CR will def pick up a few ponies and rip. Good luck!!!