Knock your cross bracing out. The pipes should extend back past the canopy area. Atleast the KS 1060's did in my friends CA Y-55. Razr remembers that Yak. It was SICK powerful!!!
If you do not have the pipes yet, please wait on cutting stuff out. There are several other things that you can do to the airframe while waiting for pipes. Sheet wings, stabs, and vertical.
But yes, the bracing will have to come out, and a tunnel will have to be made for the pipes to lie in. Once you lay the pipes in, you can do 1 of 2 things. Make frame work for the pipes. I used this method once for canisters, and worked well. I used 3/8" SQ spruce under the pipes to lie on, and then ran a piece on top, remembering to leave a bit of room for rubber grommets.
Then I ran a piece or each side of the can. Leaving room for the rubber grommets again. This way, I had good airflow over and around my cannisters in my 35% Extra. I removed the cans for a competition, and never put them back in. I have them sitting in my shop back at my other residence. Or other way you can do it is to get a piece of 1/8" ply, and cut 2 holes in it for the pipes to ride in, again leaving room for the rubber grommets. And then hollow out all around the mount for your pipes. I have previously used the 3W can mounts, and had good success, but started to break headers in my Extra. I guess I didn't have the mount in the right spot, orthe can was too high or low. They have to be PLUMB parallel to the fuse. But if you run FLEX headers, you shouldn't have a problem with breaking headers.
I wish I had taken pics of the set up, was pretty nice. You can get as elaborate with the set up as you want. I prefer the KISS method!! Keep It Simple, Stoopid!!!
Chris~