Astra dash installation kit
 

http://cgi.ebay.ca/2008-2009-SATURN-...item439b04a754

Would this be a good idea, I'm thinking of upgrading my car's mediocre sound system, should I buy this or would it be a better idea to install better speakers, subs, etc?

Will i lose the use of my steering wheel controls if I get an aftermarket head unit?
Also there's no screen on my current head unit, it shares one with the board computer in the middle like a bmw idrive sorta system, would replacing the head unit affect that?

Wow. That's a lot of money for a dash kit.

Does the deck give you the options that you want? ipod, bluetooth, MP3, sub-control? If not, upgrading will add convenience. Steering wheel controls are just another add-on.

Speakers make a huge difference for upgrades. The factory ones are usually a joke.

Subwoofers make the biggest difference on a dollar for dollar basis.

It does have mp3 but no ipod, i won't be using bluetooth, had it in my last car set it up but never used it, but ipod hookup would be great.
how much does a sub go for with a box and install?
Do i need to buy an amp to go with the sub?