[Rob99]

I have have completed this mod on my pass seat yesterday, a little delay was I needed to get a new 3/8''drill bit so had to run out for that, I did not remove seat from car like OP showed in his pic was a little leery about removing the seat belt bolt and was able to perform the drilling part with seat on its side, (you need to unbolt it)and remove plastic trim pieces using a Torx20, as posted in another thread you need to drill both sides and the seat now FULLY reclines I will post pics before I do drivers side to show a comparo of recline.
Notes:
To get a noticeable recline you will have to move seat forward a bit,
you may want to invest in a new 3/8 drill bit for this project,
by not removing seat from car you will have metal filings on the carpet when your done so you will want to vacuum those up
(at least I did want them out).
the drilling is a little intense so a powerful drill and sharp bit is important.
Furthermore I agree with another poster that this is GM's & seat vendors way of having one seat (part#)for two diff app's. (convt & coupe).