I believe someone had asked me a while ago about the L-pad. There are instructions on the 'net on how to wire one, and I used this website to calculate values:

http://www.diyaudioandvideo.com/Calculator/LPad/

It will also display a diagram when you submit. You can experiment if you want, but I decided on a 2.5db level with 4ohms, which works out neatly to one 1ohm resistor and one 12ohm.

I wired those, then of course, I wired a capacitor to cut out the low frequencies. I can't recall if I used the same capacitor as supplied by Avincar.

It has worked well for me except that the volume is low. I guess the external CD-changer inputs expect a higher volume than the typical MP3 player gives, and when I try to amplify, I get problems with ground loop type noise. Also get a bit of noise with my iPhone 4S -- my 3GS was fine.

You can wire speakers in a certain way to get a surround-sound effect (just no delay). Look up the Hafler circuit.

The other trick I did was to wire the left-front speaker(s?) out-of-phase. (Reverse the + and - .) This is because of where you sit, voices sounded weird. If you sat in the middle of the car, everything would be fine.

Avincar sold a set up speakers chosen specifically for the TSX stock system. It's not like you couldn't put other speakers in the TSX system, but whenever you work with a stock system, you have to take care to ensure that the speakers are efficient enough, because usually you're a bit limited on power. (With an aftermarket amp, speaker sensitivity often isn't an issue, as you have watts to spare!)

The stock 6x9 speakers are really boomy in a mid-bass region. This might sound pleasing to some -- it is loud -- but it's just a bit overpowering. With new speakers, there was still plenty of loudness, but interestingly, it went LOW. Now you're not going to crank up the techno and enter SPL contests, but I found it to be good enough. Listening to the stock booming is kind of annoying.

The stock tweeters probably aren't so bad, but deserve replacing. The whole system sounds better with these speaker replacements. I didn't change out the rear door speakers, but instead wired them as mentioned above.