hey orlando, i did a 155.4 with 4 3500's at 63hz in a crx, the box had the subs facing up, the aero ports facing back, and about 12" of space between the box and the tailgate. oh ya, i used 4 4" ports. also, i dont know if you already know this but the 3500's have thae exact voice coil as the 9500's. the only difference between the two are a larger magnet and an extra two spiders(dampers) i've seen another guy do 157's on the t/l with only 4 of the 3500's and 2 us amp 400x's, yes, in a crx. what i'm sayin is you can burp those subs with 4000 watts rms each, but if you do try not to burp longer than 4 seconds or so, and always wait ten minutes or so to let them cool. the 9500's have 6 soft spiders with mutiple tinsels woven through them. each lead has 5 tinsels, thats 20 tinsels on a single dual coil woofer. also they dont use any terminals, all the tinsels are pressure crimped to the vc and the leads. i think i read in your other posts that you have a 1500w amp, it would be nice if you bought one more. also, some trace cancellation can occur when multiple subs are powered with multiple amps, we know that you can level match amps yes, but this is still two channels with different power supplies. i know this may sound a little crazy but just by daisy chaining(strapping) your amps together to make a sinlge mono chn, you can gain 1 or 2 tenths of a db.
yip, strapping two amps designed to do so is essentially like running two identical mono amps in the same manner as a bridged stereo amp. you're inverting one of the two mono amps, and they work well that way.
as for what you'd hit, no real way to tell, particularly not knowing the vehicle, the rest of the system, and box specs etc.. but it should certainly get loud. zac works with DD subs in his own cars, so what he tells ya is first hand there. That should help.
are you after an SPL event car, or a daily driver?
its a daily driver for now but im upgradin for compettions, mah friend wants to buy the dd subs for 660 even though i payed 500 for 2 of them off of ebay shipped. With that money i will pay for 2 orion h2, i heard this are some bada$$ subs. And i will take yall adive and im goin 2 buy another hifonics 1500d and that will give me 1500watts rms 2 each sub. Thanx zac and glass