So you don't have to buy a new cooler, and all that stuff? All I need to buy is a bumper and foot board supports? What other steps do I need to take?
Are you talking for the '09 setup? The answer is yes, BUT that depends on how or what you want to do about the flap and light. If you want to keep a factory type look then you pretty much have to get the '09 flap and light too which greatly adds to the price of just a bumper and gussets (relative speaking). I just did mine 2 weekends ago with stock tunnel and flattened and remounted stock cooler on '08 M8 but otherwise complete '09 setup. First a thank you to ACMtnCat for having answered some of my questions ahead of time and the pictures (my sled is 400 miles from me so I wanted to have a really good idea of everything needed prior to getting to it and he was a big help). Here is my as unbiased opinion as possible. If you want to simply drill rivets out, and pop rivet everything on with minimal cutting and/or fabrication then you can buy all the '09 stuff (rear tunnel piece, cooler, end plate, flap, led light, gussets, bumper, screws, rivets). If you don't mind some more cutting and fabrication (while doing a bunch less drilling and rivetting) then you can easily keep the stock tunnel and cut it and still put on the new cooler. Finally you have the choice to keep your stock cooler and either leave it bent and remount or flatten it and remount (but the tunnel has to get shorter so at minimum it has to move). Flattening and remounting does include some more cutting but I personally like the final result better. To me, and i'll admit I have built an aluminum airplane so my fabrication and fitment levels are probably well above average, keeping the stock tunnel and rear cooler and the added time of modifying them is more than well worth the money saved. Actually in the time it would take to drill all those extra rivets you would need to drill to install the new rear tunnel section you probably could get lots of the extra cutting and fabrication finished. In the end the time may not be a whole lot different you're just doing different stuff. The way the rear end cap fits to the bumper and where the bumper attachs in the front is a set thing so as long as you understand those 'set' things then there really is no guessing involved just the labor to do it. Flattening the cooler was NOT a big deal. Yes there are plenty of people who like to make their comments because they choose not to and that is their opinion which is fine. After having done it I have ZERO concern that the cooler is ever going to give me trouble because of it. I mounted mine solidly by using the original 4 rivet locations (moved forward of course) in the front and conduit hangers in the back (going around the pipes just after they come out of the cooler). In the end you wind up without the big hole on the top of the tunnel and the only way you would know what was under mine was by looking up from the ground or knowing the rivet spacing between the two. I cannot remember exact pricing but it saves $135ish by not buying the tunnel piece and cooler but all the other '09 parts.
For the BDX kit you are cutting the stock tunnel. You still have the same options as far as coolers I guess. Keep stock and don't even move it, keep stock and move it, flatten and move, or '09 or other type of new cooler. Since the bumper on the BDX is so much longer you have the option of not even touching the cooler at all, BUT IN MY OPINION, not having the rear end cap greatly reduces the strength of rear end back there and one of the things I don't like about the BDX setup. You can add the rear end cap but then you will have to at least move the cooler. For the flap and light you have choices and depending on your choice depends on what is involved in the job. If you want the '09 flap and light then you need the end cap and have to do something with the cooler and have basically made the '09 setup with a much more expensive bumper and gussets than the Cat parts. If you want to cut and fit the stock stuff back on I believe I have seen pictures of where people have done that. It just becomes a matter of what you want.
One final little note if going to the '09 LED light the wiring connectors are different so you'll need to cut them off both sides and splice the 3 wires together. Each side has a blue and yellow and those get matched and then one side has brown and the other black and those get matched. Not a big deal.