exhaust and A/C questions

SO, a shop in town offered to take off my u-bend and resonator for 75 bucks, but my fiance really doesnt want the car to be any louder, so long as I keep my factory mufflers on, will it be much louder? Will I notice much of a power increase? I also wanted to have a high flow cat put on, but they told me the car wouldnt be able to take anything other than a factory cat, I dont believe that, but what do you guys think? I'm in California now and might just wait till I'm in Idaho to worry about the cats... BUT is this job with the resonator and u-bend worth it? and will it not upset my fiance with the new found noise? OH also, I'm interested to know if it'll help at all with gas mileage, I know that the supercharger pulley likely hurt it, along with the supercharger... but it's always something worth striving for I feel.
ALSO with my A/C, whenever I turn it off there is a loud and often long wheezing sound coming from the dashboard, is it dangerous (ie, leaking rayon)??? Is it breaking? or is it just GM?
Thanks a lot guys
PS. the pulley seal is working great! no problems to speak of.

On the CAT that doesn't sound right. I have a Magnaflow hi-flow CAT with no problems. Don't even need a 02 simulator.

With the resonator removed it will be a little louder. The only problem I note is the drone without it on long road trips. Gets annoying.

One of the best exhaust mods is to go with is a larger downpipe, hi-flow CAT, resonator delete and u-bend delete all at the same time.

On HVAC the sound is probably a vacuum actuator because it all operates with vacuum from the engine. Unless you have problems with the HVAC system I wouldn't worry about it.