I did not trim it, the only thing I notice that the plastic near the foot pegs stays loose cause the factory heel guards was holding. But other than that the rest was pretty simple. What I did to make the install pretty simple was to put in place the nerf bars, put its respective nuts and bolts, don't tighten em till the end when you are sure everything fits correctly.
So I put mine on today and all hardware was correct size and the predrilled holes all lined up. I had a issue getting the last nerf bar to line up in the arm hole. After a lil smoozing it finally lined up and worked fine. That was the hardest part alone with figuring out how to set the netting up LOL.
I installed mine on last week & had the same problem, the A arm bolt hole on the second side had to be drilled so it would fit & I did have to cutting to my plastics because they ere hitting near the pegs & I could't get the factory bolts back in there. Once there on they sure look good.
It took me 3 hours to fit mine. A few beers later and a vice for tweaking they fitted. After all this I am going to order a set for the 450r. The 450r X-factor nerfs currently fitted fix about 6" in front of the engine and vibrate like hell! I like that they fit on the lower A-arm ,No vibration.
I've had my nerfs for about a year and love them. The only problem i've had was that the rear mounting bolt head broke off on both sides. So I upgraded it to a grade 10 bolt with a grade 10 nut backing the factory nut. No problems after that.