I use the Airaid on my 03 CTD. I have no complaints, it flows good and the oil samples taken every 5000 miles show all elements including silicon to be well within factory limits. However all services done on this truck since new have been done by a cetified Cummins shop (not a f**king D/C dealship, stay as far away from them as possible). AFE and Airaid seem to be the most popular and do the best allaround job.