fmf gnarlys are a great low end pipe for trails. thats what my bro runs and he loves them. as for the airbox lid removal i think your better off cutting a 3 inch square onto the lid. this is what i did and it gets alot more air into the box but because the lid is still on it, water for the most part keeps out. if you remove the entire lid and run trails alot of water can get sucked up.