For me RockfordT210d4, SS RL-p12D2 Kicker S15L7D2
All ran from a Direct D2400, 1ohms is 1200watts 2ohms is 800.
Rockford T210 D4, made the rockford recomended "powerful encloure" It suppose to be 1.5 @ 35hz
Sound Splinter RL-p D2, made a 1.75 @32hz
Kicker S15L7 D2, made a 4 @ around 33hz
The rockford has amazing output for being only a 10" sub, I would say its SPL level is equal to or just below the RL-p, SQ wise, the RL-p hits the notes far better
RL-p I love the SQ that it gives out, but it does indead lack the output and pressure volume, I remember way back I had it sealed and there was a total lack of output, then it gotten much better after I ported it.
Kicker S15L7 I would say this is hard to beat for 220. The output is amazing, although SQ does fall behind the RL-p, the L7 does it job in the box that kicker recomends, it gets loud and low.
All the subs go for about $200-250, but the T2 I got for 90, RL-p for 220ish during the GB, L7 for little under 220.