If you have the ALLison tranny you may want to hold up on those 285's. My dealer told me the tranny couldn't be reprogramed and I might have trouble with the shift pattern and warranty claims. i changed oil and filter at 3K and will probaly go 5K intervals until I get 20K on the truck and then I'll switch to synthetic and longer change intervals, that is if GM will approve the practice. Have a Nicktane pre fuel filter and think its worth it. To much hassele to put a post filter in and don't think its worth the cost because ypou still have to change the OEM at sceduled intervals toprotect your warranty. Going to change the Nicktane catipillar filtar when its got 10K on it. Will cut it open and see what it looks like then and determine how long I'll leave the replacement filter in. Will still change the OEM at scheduked intervals. That juice system is for those that want to hot rod thier diesels, it will also void your warranty claims if left on when you go in for service. Some dealers even look for eveidence that you had a Juice or similar set up installed. Have friend that has similar set up plus lots of other stuff and his truck will lay the rubber down and create big smoke cloud. I think he just gave up his warranty rights, he can afford it.