So I've gone through two different CAIs. The first one I had was (roughly) 2.25" piping, two pipes, one between the manifold and TB, and one that bent down into the fender well.

The one I have now has two 3" diameter pipes, one coming from the TB into the resonator hole, and then one going to the filter from there. This one is wedged in because it A) didn't come with a shorter IM/TB pipe, and/or B) it was designed for the stock accordion tube that allows for more or less length and travel. It is so wedged in there, I had to modify the coupler several times, and put a piece of vacuum hose on the fender to keep the pipe from rubbing away.

I almost feel like the 3" piping allows for more air flow, even though the throttle body is bottlenecking air flow with it's 2.25" diameter. I noticed a slightly better throttle response and overall pull with the 3" piping, but this might just be a placebo effect.

My question is: Am I actually getting more power due to the increase in diameter? Is 3" too much? Would 2.75" work just as well? Or is there any difference?

I'm trying to find a better system because the intake I have now has the dreaded foghorn effect, and it makes me sound like I have a bad wheel bearing or something. Not only that, but there is no way that the way I have it jammed in there is good for the piping.

 

I have an Iceman Intake on my '05 sxt, was on there when i bought it. if i remember correctly, on any 03+ model, we are getting almost zero benefit from a CAI, for a couple reasons.
1) Factory airbox flows more air than the engine can use anyway
2) the ecu in the 03+ models, basically "retards" the engine to offset any basic mods.
it has the benchmarks of the factory tune and works hard to maintain those levels.
I'm sure someone else can explain it much better...

 

 

That's about it. Increased airflow is only going to help when the engine needs more air than it is currently getting. If you have a stock engine, a larger intake isn't going to do anything as stock intakes flow plenty of air to the engine in factory-form. That, and the NGC system is horrible when it comes to mods. I mean, if you tweak several things (intake, TB, exhaust and so on), you'll get a little out of it.

 

That's what I thought. I got my new intake and to my disdain, instead of getting 2.75" piping, it came with 2.5", regardless of advertised size. But, it works as well and fits a lot better than my previous intake, even though it still makes the foghorn noise. I will be getting that fixed soon, however.