I think it also depends on what your budget is aswell. If you are looking for a quality stealth install then from the positive comments on this forum the AndyMac solution is a good one. I considered the JL Audio 6.5 kit, but I could not justify the spend due to the amount of time I use my car! Therefore I took a chance on the sub enclosure you have the link to and it has a nice rebate for the sub to sink in to, but could probably do with being built with thicker MDF. I then bought a JBL GTO-804 8" subwoofer which is rated at 200w RMS for around £40 including delivery. Now I doubt that this sub enclosure has the precise volume of air required for this subwoofer as it is not sold as a kit, but you get what you pay for.
I will admit that I used the AndyMac instructions to removed the interior panels etc, 'So thank you for sharing this'! and removed the infamous tupperware subwoofer and cd changer, which I had no intentions of refitting the latter, which was good as it won't fit, not like with AndyMac's. In my car this enclosure did need a bit of persuasion to go far enough back that when you refit the left side boot panel that the door flap stays on and does not foul the subwoofer.
As I already had a 200w Alpine amplifer I installed this in the same place as recommended (With some a small amount of ****** knuckles for my efforts and a couple of quid in the swear box!)
The overall sound is good considering I took out 12" Sub, thou if you are fitting a small sub you are not really going to shake the door mirrors with air pressure, but still good enough for me. I will say that I was impressed with the quality and the weight of the JBL unit and I would say it truth due to it's size it is more of a mid bass, but still deep enough for Hip Hop type of stuff I like and the Mrs hates!
Oh just one more thing, you will probably have to remove this enclosure to get to change any blown bulbs etc on that side, but probably not an issue with AndyMacs, but good luck either way
Ian