You can only cut and drill so many holes before you take away from the structual integrity of the hull, I try to place speakers where they sound best, others may feel it sounds better other places, but I always put high's up top along with full range and subs go down low, If I placed the subs above the 8's it would drown out part of the sound. I may find that I will add subs down the road but for me I would have to build a box, this is partly with the understanding that you can still hit waves and not crack the hull, if I had 4 8's and then 2 12's mounted in the sides it would crack under stress, verything requires carefull placement in a boat.
I only found these speakers by going to a local car audio shop, the jl audio 7.7's I was looking at where almost $300 per set, don't get me wrong they sound very nice however these offer more/better bass and brighter tweeters on them.
The other problem is the weight of the sub, lets say I installed the matching 10" memphis sub, it is very heavy and if installed just into the hull/upper deck it would rip the screws out/crack the fiberglass from the stress, great care must be taken.
These speakers will all be installed the same way as would they on a 40' fountain out at sea jumping 4-6 foot waves to prevent any problems.
Usually all the better higher end speakers have heavyier magnets on them, I stopped buying items just because of a name a long time ago, most times you are just paying for the name sometimes not. Memphis is known but not by all and its surely not carried in any local stores.
As I stated this is also a test for me, once installed I will determain if subs are needed or not, this is also to advertise my work and the audio shops work/equipment.
I will usually only recommend items I have tested myself or have already installed which is one in the same, I have not to date installed any full range 8's, only 6.5's or 6x9's in terms of the largest otherwise small speakers and subs, this is new to try.
Rockford fosgate also makes an 8 full range from what ive heard very nice as well, however their car audio line lost my interest after 2000-2001, they seem to be doing good in marine audio though.
Also note how even some bazzoka speakers are have way desent in marine as well, yet I can show of some junk models as well from almost every manufacture with some exceptions, jl audio, memphis audio, rockford fosgate all 3 seem to have no junk lines, now when looking at all the others for say clarion,jbl,sony,jvc, yadda yadda and oh pioneer, they all have very cheap to ok better ones. Poly planar is another with ok speakers.