DVX has the same 36mm Mikuni BSR carb that the LTZ and KFX have used since 2003 and it still has it for 2005. The 2005 LTZ and KFX got a 37mm version of the carb along with other suspension, clutch, and cam timing upgrades that the DVX didnt get.

And the DG xcellerator is one of the worst mass-produced atv exhausts availible on the market. Its cheap for a reason and doesnt belong on a high performance atv.

The 2003-2005 DVX and 2003-2004 KFX and LTZ 400 atvs are all mechanically identical save for some plastic and seat differences.

Here is a little info for you: DVX carb info, 2004 LTZ specs