AFR, o2 sensor, or MAF problem?

[namwons_240]

ok heres my problem

when i installed my sr, i installed an HKS AFR also and started messing with idle and rpm fuel adjustments. this cause a loud crack noise from my exaust, like a fire cracker, is it detonating? no visible white lean smoke or black rich smoke though. then i resest it all back to 0% so it should be back to stock right? well i then bought and installed a boost and a/f gauge and the a/f gauge read lean, like read lean, but no smoke, and never goes back and forth at idle like i thought i would. did i fry my o2 sensor or wire my gauge to the wrong wire? so then cranked my AFR to 30-45% across the whole range and still same lean reading. Oh and im using a Z31 MAF not Z32, could that be the prob because i have AFR set to Z32 in? I need answers to these questions before i am confident to crank up the boost.

Sorry for the long thead but im mostly stock atm exept for full exaust, walbro, and custom starion front mount.

Thanks, any help much appreciated.

[namwons_240]

Oh and the car seems to run strong but if it is lean i want to fix the problem asap.