airbox / air intake 4.8 vs 5.3 vs 6.0


New Member
Well, I'm new to trucks having picked up my first late last year - a 2002 Silverado RCSB 4.8L with a 5spd.
The previous owner had tried to upgrade a few things but didn't accomplish any of it to my liking or standards of workmanship. What I mean is that some of the work done was not very neat. One of the mods was a K&N air intake with one of the big fat cone filters. (as a side note, I thought it was cute that there was a Toronado wedged up in the plastic tube a few inches before the throttle body! amazing... it was an authentic "tornado" branded one too!) When I looked into the available info on the intake (57-3021), K&N claims that there's a 9hp (4% increase) gain just shy of redline. The test seems to document that it was done on a 5.3L. There is virtually nothing different below 3500 rpm. 99% of my driving is below 3500 rpm.

Now, I"m late to the game here, admittedly, but I've learned a few things in the last 6 months.

basically the airbox and design is pretty much the same for 20 years... I'm not sure but from what I understand the airbox (or at the very least, the use of the same air filter based on part #s) seems to be the same until 2019.
the 1999 to 2006 models share the exact same airbox whether 4.8 or 5.3 or 6.0L!

This leads me to believe that there is zero gain to be realized on any 4.8L by "upgrading" the airbox.
If the same airbox can supply enough air for a 6.0L , how could it possibly be undersized in any way for a 4.8L? Put another way, if the 6.0L is using the same 4.8L air box, there could easily be some power left on the table by upgrading that for those with the bigger engines?

Needless to say, I've gone back to an oem airbox (the one I got from the scrap yard was from a 6.0L) and I don't notice anything really different at all. It's a lot more quiet and I'm also intrigued by the visual air filter guage which I find pretty cool. I also like that paper filters are simply better filters keeping my high mileage truck hopefully around a bit longer.

I'd welcome your thoughts or discoveries on the air intake used on these trucks.


You did good removing that K&N filter. As shown in this recent Project Farm video, it doesn't filter that well compared to good ol' paper.

The attraction of the aftermarket air intakes is the noise they produce (or don't muffle). CAI's have been proven to produce 0 HP or even reduce it.

There's way more power to be gained with other mods like exhaust, cams and tunes.


KN is poison to an engine. Studies been out for many years showing they allow 97% more particulate through. I can't believe so many uneducated people still by them based on BS.


Well-Known Member
If they did what they are called they might would do some good. "Cold" air intakes. Unfortunately most of the ones sold today are merely for looks and dont actually cool the air at all... What i cant figure is why anyone would put 1 on an Envoy or GM truck when they come with almost the exact same setup already minus the shiny pipe.

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