iMR2 had this to say about the bar installed
on his car above:
WOW!
If there’s a first thing to get for the Spyder, this is definitely one
of them. I thought the chassis was pretty stiff already, but after
installing the rollbar I noticed a much stiffer chassis.
After the install I immediately tugged and pulled on it making sure all
was tight, then took her out for a spin and headed out for the nearest
bumpy road. To my surprise, the car was firm and gave more feedback of
the road than without the bar. Next I headed to a local canyon I
normally take the Spyder and put it through the paces. Again, there was
better feedback of the road. The ride also felt stiffer overall,
especially the rearend.
One thing I did notice immediately was the road noise. Not so much
that it increased, but the interior sounds different. Nothing bad, but
an observation. My guess is that the bar probably absorbs the road
conditions and that’s what I’m feeling and hearing???. The interior
noise just sounds and feels different, it’s hard to explain, but
something you’d know after having gotten used to a certain sound and
feel for awhile. I plan on filling the rollbar with foam to strengthen
it even further, so this may change again for me.
The install was pretty straight forward. Total of 4 hours. The most
time consuming part was trimming the plastic side covers for the bar to
fit. I spent 3 hours alone on this. There was a total of 3 pieces for a
total of 4 holes; inorder for the bar’s mounting brackets to fit
correctly. I took my time here to fit the plastic trimmings. I put and
pulled off the plastic trims numerous times over and over after each cut
or grind I made. Making sure it was going to fit real snug for that
factory finish look. As they say “measure twice, cut only once”. I
used a Dremel rotary power tool and used only two bits. The cutoff wheel
and the sanding wheel. I gotta hand it to Dave for providing a template
that was dang near perfect and served as a great starting point. Minor
modifications were made to suit a better fitment and should be expected
as each car will be a little different from one another.The bar itself
bolted right into place with the new longer bolts provided with the bar.
A Note for those that will be installing one, the bar may initially
look like it doesn’t fit with the side chassis mounting brackets.
That’s because those bracket aren’t really all that firm to begin
with and may sit a little off. Just put to the bolt through the bar and
start threading it to the chassis bracket and all will line up. There
are also 2 longer bolts that come with the bar. If you don't look
carefully, you'll miss it. Those 2 longer ones are for the rear mounting
structure.
Here are a few pictures of my bar installed. (Picture set above) The
first picture shows the bar right underneath the softop. It does not
make contact with it whatsoever. Even when putting the top up or down.
There's about 3/4" gap between the bar and the top. And the best
part is you can't even tell it's there through the rearview mirror
unless you look for it. No obstruction of view at all.
Brief Instructions For AutoPower Rollbar install. This is just one of
many possible ways to do it.
Make a couple of photocopies of the template, just incase the dog
eats it. 
1) Lower convertible top down, but do not lock it down in place
throughout the install process.
2) Recline both seats forward for access to the rear, open the storage
compartment and remove the 2 side panels inside there.
3) Using a screwdriver or something that will allow you to push in the
center piece of the 2 piece clips that hold the trims in place. Do this
to all of the clips holding the 3 trimmings that will need to be
modified. The clips lift off very easily.
4) With a 14MM open-end wrench remove the bolts from both driver and
passenger side that holds the seat belts in place next to the doorsill.
This will allow you to pass the belt through the trim when taking it
out. Adjusting the seat forward will help in accessing the bolts easier.
5) Remove the side trim panels, then remove the middle trim panel.
You’ll need to remove the windblocker and pull latch for the
convertible holdown to get it off.
6) Remove the white clips from the side trims. There are 2 per side.
This will make it easier pulling off and on several times. Remeber to
replace them during your final install.
7) Place the rollbar in place and bolt it down firm, but don't tighten
it all the way. You’ll be taking it back off. There are 6 Bolts
supplied with the bar. 2 are longer. Those 2 (1 per side) will replace
the factory bolts that will be too short to mount the bar. The other 4
bolts will go on the side bracket mount where there are no factory bolts
at all. I did use washers, which were not provided. I didn't want to run
this risk of stripping a stud or bolt.
8) This is where you want to take your time, and the results will show.
Modify and cut the 2 side trims using the template. Measure twice, cut
once.
9) With the bar in place, try fitting the side trims, until you feel
it’s to your satisfaction.
10) Once both side trims are cut and fit properly, unbolt the bar and
remove it from the car.
11) With the Bar removed, replace the middle trim first, then the 2 side
trims back on the car. Use a couple of the clips to make sure they are
seated correctly on the car.
12) At this point only the side trims have been modified. Now you must
complete the circle for the bar on the middle trim, because no template
is provided for it. Take a sharpie marker and draw the circle complete
on the middle trim. After you have drawn the completion of the circles
on both sides, remove all the plastic trimmings and proceed to modify
the middle piece according to your marks.
13) Install the rollbar back into the car firm but don't tighten all the
way.
14) With all of the trims now modified to fit the bar, install the
middle one first. You’ll have to be creative in flexing the plastic
parts around to fit in.
15) Once the middle piece is in, make sure that it fits properly, paying
close attention to the holes for the clips lining up with their
respective holes. If not take it back off and grind some more off where
needed. Make sure the holes for the clips line up or else you won’t be
able to secure it.
16) When you finally have the middle fitted correctly, proceed to work
on the 2 side trim panels.
17) Cut and grind until they fit right.
18) When all trimming is complete, tighten down the bolts to the bar and
replace the 2 white clips for each side trim. Remember to thread the
seatbelt back through the panel.
19) Replace and secure the seatbelts with the bolts previously removed.
20) Replace the 2 side trims that go inside the storage compartment.
21) Go ride over some bumps and hit the canyons.
22) Write your own review of the bar, process, etc. 
Let me know if something isn't clear and I'll try to explain clearer.
Here’s the template showing what mods I made to make it fit. Yours
may be different.

Click Image to Enlarge
Another SpyderMagazine member, Devin, also purchased and
installed the bar and his comments and pictures are shared below:
I installed the rollbar today. It was relatively
painless. The only problem that you all might need to watch out for is
that one of the screwholes (the passenger side screw that goes into
where the hardtop mounts) was a hair off. Since I didn't have the tools,
I called up Dave and he said to come down and they'd fix it. All that
entailed in fixing it was taking a file to it and filing off an extra
3mm or so, and it worked fine. It happened on his car too, so be sure to
have a metal file handy, just in case.
Here are some pictures I took to go along with iMR2's instructions.