I wont to upgrade my current sub & amp (replacing my Dayton DVC 15" & PE 250watt plate amp). My sono is a 220 liter tuned at around 17hz With what I have in it know. If you need sizes it measures at 48"length by 20" dim using a 6" by 24" flared port. I have tried using winsid & bassboxpro but either I'm not doing something right or my computer isn't compatible with the programs because I cannot get my computer to load them right, So this is why I'm after your help. What I am after is just getting a little more output & possible being able to play a little lower & cleaner. There is no way I can modify the enclosure other than making it a little shorter if necessary or changing the driver end cap ( I'll explain). Ok that said I was wonting to go with the AV15" & a Adire HS500 amp, witch I was told before should sound pretty good in my enclosure as is. But I also seen the Acoustic Visions has there Maelstrom 18" on sale right now so it got my attion. My question is witch of these two drivers would be a better choice in my enclosure or would either of them out perform my current set up by much? I would like to be able to just drop something in & go but I can easily change the endcap to accommodate the Maelstrom if it would be the better choice but I don't know what would. I would just build another enclosure but this is kinda a last minute decision that I didn't think I was gonna do until now, & I just spent a good couple of days veneering my sono in oak veneer so I don't wont to change it. I would be grateful for any advice anyone could offer. Thanks in advance for any help.