Well I'm just back from my audio installer. And here are the settings I had to use on my equalizer to flatten the response on my 2005 G35x Bose system with aftermarket amps and speakers all around.

I had him do a pink noise test with a 1/3 octave RTA and we adjusted my EQ for a near flat response shaped like a happy smile. And what we found was quite interesting. Here are my settings after equalization on my EQ:

32 0
48 0
64 0
90 0
125 0
180 0
250 +1db
500 -3db
1000 -2db
2000 +12db
4000 +3db
8000 +6db
16000 -3db

With these setting the response is completely flat from about 250Hz to 8000Hz with Bass and Treble both set to neutral 0 on the deck.

As you can see the stock system has a BIG dip at 2000 Hz (2500Hz on his RTA) as my EQ only has 1/2 and single octave adjustment the closest setting was at 2000 Hz. regardless it was off by 12 db !!

For those of you interested I installed Focal 165K2P's in the front with 165CV's in the rear. The sub I chose was a Boston Acoustic's G510 (dual 4 ohm voice coil). Amps were a 4 channel Audison (LRx4.300) 4x65 watts and a single channel Audision (SRx1) 1x350 watts. I have a sub volume control installed in the cigarette ashtray location. And finally an AudioControl LC6 was used as the LOC and the EQ was a old (10years) LA Sound LEQ1026.