recently my right rear sub blew out and sounded terrible.
i searched the forums for a decent sub for the factory system and factory head unit,but did not seem to find anything that fit my needs.
after a little web surfing i found this discontinued sub from infinty.
the basslink ii is a passive 10 inch square sub that has 250 watts from an amp built in.
install is very simple "please note i have coupe,so i do not know if all access spot exist in roadster"

8 or 10 gauge kit seems to fit best
i have a 100 amp fuse from an old sub "will probably switch it to around 40 later"

i ran my positive wire through a access hole found behind the battery.
that wire will pop out to the top right area above the factory amp
you can now run that along the trim to reach the back wall by the rear sub.

at this point i had the carpet pulled back of the rear passenger sub.since this sub has never sounded well i decided to hijack its 4 pin that was powering it .the infinty sub will come with a 4 pin extender,it has 2 solid and 2 stripe wires. make sure the soldered wire end is in the right slot and the wires match.you will now have 25 feet of cable to run to the back along the power wire from the battery.

to the top left of the sub is another access hole to reach the rear cabin u can easily push through both positive and 4 pin through. the cables will spit out the back side.
i hade to pull back the carpet along the fuel tank and the carpet to the right to pull the cables through.

now all that is left is mounting the sub and running ground and remote control.
i found a nice grounding spot behind the access panel to the rear driver side lights.there is a bolt in the far back to the body i removed .i then sanded the area to use as a good ground contact. run the wire under the trim to the back of the sub.

the remote control level has plenty of legnth. run in to the front via the trim on the driver side,tuck n go. i drilled mine to the left under the steering wheel.

plug all cables into the sub in there respected places
"4 pin goes to rear input"
this will also act as a remote on and of for the amp so no worries there.

there should only be 4 cables plugged into the amp at this point
positive
ground
4 pin line
remote control for bass

to keep the sub in place i used a sheet of wood that was near the size of the trunk mat.
i drilled the carpet to the wood then proceeded to drill the sub to the carpeted wood trunk mat.to keep to mat from sliding i padded it with go no where mats which will help hold it in place and the sheet of wood will not vibrate .


i think that the best factory head unit setting is bass -2 and treble +2
this will help prevent the door speakers from rattling at high volume
the amp has boost and hertz control.
tune it from there to get the sound you are looking for
put the bass bass booster near high and use the given controller for bass levels
i think thats pretty much it

i personally feel this setup it is near perfect .the bass blends perfect with the door speakers and tweeters. perfect amount of sound and very nice quality.
we used a high wattage 4 pin to carry the orignal low frequnecy so th the sub will hit as the factory amp would have it. nice crisp and clean.

`i will try and grab some more detailed photos when it is not so hot outside.
thanks for reading hope it helped someone

here is the finished product.

 

Good writeup, but these aren't even available anymore, are they? I wonder what to do with it in a roadster?

 

Yes you a correct these are no longer up for retail sale .i purchased this for 250$ brand new on eBay .