Bass Exciter build

[dublin78]

OK
I have just bought 2 sets of these drivers: http://cgi.ebay.co.uk/New-Alcone-BX1...QQcmdZViewItem
I had seen them on www.lautsprechershop.de/english/index_hifi.htm previously, but had been to stingie to splash out on them at the time.
The ebay offer is fantastic value for money. They look really nicely made, and were designed by Ralph Mantel.
Does anyone have any experience of these?
Initially (for space reasons) I am going to build 17 litre sealed enclosures as per Strassacker recommendation.
Any views?

[dublin78]

Specification BX10

250mm top class sub bass driver with coated paper cone, twin magnet, rubber surround, ventilated magnet system and sheet steel basket.

output (continuous/programme): 150/300 Watt
impedance: 4 Ohm
resonance frequency fs: 30 Hz
DC resistance Rdc: 3.5 Ohm
mechanical Q factor : 6.76
electrical Q factor Qes: 0.36
total Q factor Qts: 0.34
equivalent volume of compliance Vas: 50.07 L
voice coil inductance at 1 kHz: 3.12 mH
effective mechanical mass incl. air load Mms: 91.3 g
mechanical compliance Cms: 0.30 mm/N
effective piston radiating area Sd: 365 cm2
electromagnetic force factor BI: 13.11 N/A
sensitivity (2.83V /1m/1kHz): 87 dB
voice coil height: 23.5 mm
voice coil layers: 4
outside diameter: 258 mms
cut-out required: 229 mm
mounting depth: 133 mm
countersunk depth: 11 mm
cone diameter: 169 mm
mounting holes: 8x5 mm on 250 mm diameter circle

Specification BX10P

The passive radiator BXP10 was developed in conjunction with the BX10 driver. The BXP10's excursion is huge, double compared with the BX10 which is a piece of cake for the passive. It incorporates a rigid MDFcoated cone, and is easy to tune by attaching weights on the inside.

outside diameter: 255 mm
cut-out required: 223 mm
mounting depth: 74 mm
countersunk depth: 7 mm
cone weight: 180 g
resonance frequency in 17 litre cabinet: 46 Hz
cone diameter: 169 mm
surround width: 35 mm
effective piston radiating area Sd: 365 cm2
mounting holes: 8x5 mm on 245 mm circle