@9BL
Pioneer D Series surely fall in the category of Alpine Type R, JBL GTO and Infinity KAPPA.
But they are simply not good enough, this fact is also evident with the price difference that prevails between KAPPA/Type R.
You can power a GTO or Type R with your Alpine F450, and feel the difference.
At more then 90% output D series can be blowed easily, because they cannot take that much power, but Type R and Infinity KAPPA will remain rock solid.
Polkaudio DB and MOMO series is the best of the best, regardless of price or any competition, anyone can opt for them with eyes closed, just make sure they are real polks.
Kicker updated DS series is also very good, which came after 2007, but the Jewel of crown is KS6930, which compares brilliantly to Type R, but they are expensive and still lags behind DB and MOMO series polk.
I would vote highly for polkaudio, real pro stuff.
Regards