BDL Fyshwick have done all my Alarm systems - No complaints.
Audiotech - tuggeranong have done 4 full stereo systems - No complaints
Audiotech did my Double din HU and speakers in the 34 12months ago - all is good
They just did my R32 GTR about 2 months ago.
and last week I got them to replace the Airial Amplifier and earthed it, and Connected airial to AC to fix an inherint problem with all R32's radio reception problem.
As Ive used Tony (Audiotech) alot I get taken care of pretty well.
Cant go wrong with either shops. With using a shop you can go back and have it fixed. In DIY's your left wondering if you get it wrong.
Harder then to take it to a shop to resolve any issues.
I'd take it to Warren BDL Fyshwick if your new, These SAU guys dont praise easily but rag on shops pretty quick if there not happy.
My 2cents worth
*edit* I would never use JB.