Well how old is you chain and sprocket that you have on there now because if they are worn then I would go replacing both sprockets and the chain otherwise I would just do what was mentioned before.

 

is a 15 the best way to go for a slightly modded DS, or is 14 a better way to go. Obviously top speed will suffer, but how much do you gain by going down on tooth say from a 16 to a 15, then a 15 toa 14. Also for the rear sprocket, is a 40 too much, too little, how does it compare to one that is bigger/smaller?

 

What kind of mods do you have? Before I rebuilt mine all I had was a full pipe, cdi and a K&N, and a Lectron46 and with a 15 tooth on the front and 40 on the rear I had to climb hills in 2nd gear. When I put the 14 on I was in 3rd, and could keep up with most everything.

Just remember, going down 1 tooth in the front is like going down 4 in the rear, yes with a 14 top end will suffer a little but I think you should be ok.

 

I dropped mine down to a 14T front with 22inch rear tires and it was just about the same as the factory 16T front and stock 20 inch rear tires. Also I did not have to remove any links from the chain, but it was put on when my quad only had 10hrs on it since brand new. I still have not run out of adjustment after 3 years now. Still running the factory chain, and still have adjustment left.

 

well my chain is stock i bought the ds in august 06. new.
the rear sprocket is like new and the chain is in good shape.
so im good there