Not sure what a S&B cold air intake is but everyone I've ever seen has a K&N type cone filter and eliminates the stock air box...is that correct?
The absolute fastest way to kill a good diesel is to put crap filtration on the intake, (such as a K&N), and/or put a tuner on it that adds stress and heat to the engine. It's been proven so many times just in my own first hand observation that I've lost count.
I made a small cottage industry at one time buying "dusted" diesel trucks that someone had put "cold air" intakes on and sucked in dirt, destroying the seal between the rings and cylinder walls. Modern diesel PU trucks run somewhere around 400 psi of cylinder compression stock and when it drops due to improper maintenance, all of the crap tuners on earth won't put Humpty Dumpty back together again.
That's where I came in, buying cheap and rebuilding, with proper filtration restored, of course. My 1999 Ford Power Stroke, (and every other Super Duty diesel ever made), has cold air intake from the factory. There is a huge snorkel coming off the air box to the front grille. Every aftermarket crap intake I've seen sucks hot air from under the hood and eliminates the stock airbag and snorkel. Also, if you do not somehow preserve the factory IAT sensor, (intake air temp inside of air box), the ECU thinks that it's 20 below zero outside all the time and you have a rich mixture w terrible performance and fuel economy.
Seriously, designing an adequate air filter and box is probably the least challenging thing the engineers had to do when they designed your truck. There is no government regulation or design restriction interfering w putting a sufficient size filter in the flows enough air. K&N uses bigger hole in an oiled, crap filter and they are snake oil, end of story. They are handy in the rare instances that a modified or antique engine needs some minimal filtration and a good stock solution doesn't exist but on a modern diesel, which always have excellent filtration, they are extremely unwise. That's not just my internet opinion, it's documented well. Use the mouse on your computer.
