Sony CDX-GT decks, 120dB Sig-Noise?

My uncle is looking at one of these decks (GT300) and I am trying to talk him into getting an Alpine for about the same price (CDA-9847). What is the deal with the really high signal to noise ratios on the Sony CDX-GTXXX decks? They list 120dB on every website I have seen them listed on. Is that just a blatant lie, marketing gimmick, etc.? All of the other brands seem to have 105dB. Also, what else do you guys reccomend in the $150-$175 range that can play MP3's and is XM satellite ready? Thanks guys.

Just inflated numbers, like peak power outputs.  For the price, the cda-9847 is tough to beat, and does not have the typical problems of the higher end Alpines with glide touch.  I'm sure Rob or someone else can give you a number for an Eclipse.  Look into Kenwood as well, and stay away from Sony and Pioneer (my opinion).My ex once told me I have a perfect face for radio.

At our shop we've tried many of new sony heads, gt 100, 200, 300. The alpines still sounded fuller and cleaner. I'd stick with the alpine.2003 Ranger EXT Cab

Sony CDXC90, XDP210EQ

Alpine SPX177A

JBL p1020, BP600.1