Taming large 1Khz peak, without EQ

[eRiCdWoNg]

...I recently constructed a car audio system out of DIY parts from Madisound. I'm using a 8" Silver Flute woofer, and right above that a 4" Vifa midrange driver in the doors of my car, and on the dash near the A pillars, the Vifa ring radiator tweeters. Ive built plenty of woofer enclosures but I dont have much experience in terms of midrange drivers.

Anyway, the Vifa 4" midrange I'm having a problem with, I have a sharp peak in the response at 1K. It makes the system sound VERY shouty and is fatiguing to listen to. Based my on my RTA, it is a 7-10 dB peak. I used my electronic 1/3 octave graphic EQ with 1000 Hz set at -10 to offset the problem.

I'm wondering if anything can be done non-electronically to get to the route of the problem. I think the main thing is about 1/3 of the driver is covered by the door skin of the car and then alot of it is reflecting off of the lower dash, so that is creating a nasty peak.

I'm thinking to stuff as much sound absorbing material behind the part of the door skin that is being covered. What about behind the midrange driver? Right now I have nothing, it just radiates into the door.

Here is the anechoic response from the MFG and a pic of the driver.