the orion amp really wakes up under 0.5 ohm. At 1 ohm its really not that special of an amp. Infact my mephis 4kw was 2.9 db louder in a drop in test at 1 ohm on 1 12 volt batt.

If you can run the 2500d at 0.35 ohm for burps it should do a whole lot better though. I tried mine at 0.25 and couldnt get a full burp off reliably but I didnt mess with different enclosures to get more box rise.

 

thanks ill give that a try