Stock Intake System vs. C.I.A

I have used both and various setup as with bigger MAF and better MAF curves with custom tunes and a wide range of differnt C.A.I setup as well. I have noticed that there is actually seems to be a loss of power and torque, not to mention leaning out a various points due to the turbulence of most C.A.I. I have also been told that if the diameter is bigger than the MAF and the Thottlebody that your application is setup with you could even cause a vacuum in the air intake system, which is bad.

I am wondering if all this is true or does a 'good' CAI do what it is suppose to? What is a 'good' CAI setup?
Which filter to use with the right one?

What is the best size MAF diameter for a 70mm T/B setup?
I have an 80mm C&L that I want to use, but haven't decided how to work it in just yet, plus I need a curve to dial it in correctly and cannot seem to find one. C&L engineers weren't any help either, I think that techs are getting dumber everywhere or is it just me. They said that no matter what tube I used on this meter that I wouldn't be able to get it adjusted out, that it would always be lean... Well I know as well as the other EEC tuners out there that it doesn't matter what tube is in it or what size it is [to a certain degree] as long as you adjust the curve for it.

Any thoughts or suggestions are welcome and very appreciated.

i think i had the same problem on my 87 that i put mass air on if you havnt got a chip yet that would help i had an e cam with gt 40 p heads and an adjustable fuel presure regulator help my car alot it seemed