Hi Des
Welcome to the forum!
Could you add a post to the "Where you heard about the forum" Topic... Just so we know...
Anyway, making gamma's sound better...
I have a Gamma, 6 Disc, Apple iPod 20gb MP3, Rockford Fosgate 2x 30w RMS amp for front Focal 165 component speakers and a Kicker 120w RMS amp running a 12" Sub in a sealed box.
It all sounds lovely!
First of all, you'll need a Gamma to 2x Stereo Phono adapter. Music World in Sheffield sell them... A company called Autoleads makes them...
Then you'll need a long (5m) stereo phono cable to run from the back of the Gamma to the boot...
Then you'll need to run a live power lead from your battery (with a fuse near to the battery) all the way through the car to the boot...
Then you'll need an earth wire going from underneath your rear seat (screwed to bare metal) into your boot...
Then it gets interesting!
If you want a bit more bass you can get a powered sub (Vibe do a good one which isn't too big) which is a box with an amp and subwoofer built in.
Halfords sell them. (This is the very easiest way to get started in bass - The other option is to get a separate amp and sub-in-a-box)
If you want more power from your speakers, you'll need some new speakers (woofers and tweeters)... I wholeheartedly recommend Focal Speakers, and you'll need an amp and some speaker wire
If you want more sound from your (uprated) speakers AND more bass, you'll need both of the above!
OR, you could get a 4 channel amp (if you're only using front speakers and a sub - Like I have) or a 5 channel amp (if you want 4 speakers and a sub)
Don't go for 6"x9"s.
To start with, I'd probably go for one of the Vibe all-in-one boxes and go from there... I ran standard speakers/gamma/amp and sub combo for a while and it is a lot better than not having a sub... Road noise kills bass from normal speakers, so a sub will reinforce this bass so it doesn't get drowned out by road noise. Even a small sub will make a lot of difference if you don't require it to go LOUD...
It's a bit of a bug once you start though... If you get a sub, it will be fine for a while, but then you'll want better speakers... You'll get new speakers, they'll sound better, but then you'll want to amp them... You'll amp them, they'll sound amazing, but then you'll want a bigger sub/amp combo!... Etc, etc until you've got a Playstation 2 and a TV in the dash!!!
Hope this helps, BUT, I recommend that you get a professional company to install whatever you buy unless you've done it before and are confident with this sort of thing. If you've never done it before and have a go, there's a very real risk of fire/buggering up your car/it sounding crap!
Again, Welcome to the Forum! Tell all your friends about it! (It's only been live for around a month, so that's why it's not mega busy at the moment)