there have been countless posts on this topic in the past. you could literally spend a day or two reading in the archives. I think most would agree single pipes are good for the average rider. when combined with a programer and intake they improve greatly upon stock. my knowlege base is mainly from this forumand you will find there are a few with other opinions. the LTEs are a great choice if you are trying to get the max out of your quad, or have bigger plans in store other than the 3 basic mods. I have the LTEs and am very happy with them. I initially bought them just cause I thought the duals looked really cool. I just got lucky when I realized how good they were.
when I put mine on I did it in conjunction with the PCIII and intake. compared to stock its a totally different quad. I also did the 15T front drive gear and had to get used to the power. I ride mainly in the sand and the front end still comes up on demand. pulls real hard through all the gears. never rode one with just the pipe.