Thank you so much Nickshu for this Five Stars Topic.
And thanks a lot to Quadcammer that posted in my topic, the reference on yours.

I come from the 986 “chapter”, and have the exact same problem, i.e.: hate the “mushy brake pedal” feel of the OEM car.
(The only positive things of it, ..is the feeling that you have to bleed every track days !)

Note:
I have Brembo big brake kit on my Boxster (large floating rotors and 6 pistons calipers) and just want a FIRM (normal sport car) brake feel. I also got the feeling that the large calipers even made the feeling a little bit worse than the original !
By the way, ..after 30 years non stop of multi 911 (including 11 years of 996), you could not believe how great I feel about a Boxster. Nothing beat having the engine at the right position !
(..or: why I’m on the “986 Chapter” !)
After going for an install process of a TRW PMN166, ..I found the mismatch on outlet tubes !
(or, good for back to OEM and ..another full bleeding session !)

Thanks again, I think I may also go on adapter solution too.
(Or trying to get another line new or from a dismantler, and cut the bubble, remove the 10mm nut, to replace it by a “small” tube 12mm nut (made for 4.6mm tube)
(the “common” 12mm nuts seems to be designed for 5.8mm tubes) and rebuild the bubble.
This later solution would have the advantage to suppress the need of an adapter.

By the way, about this upgrade, I also observed during this tentative that the mounting of the GT3 M.C. on the booster is different at the level of the sealing between the booster and the MC : on the OEM MC, at least on the 986, the sealing is done the “axial way” with an O-Ring, while on the “GT3” one, the sealing is done in the “vertical plate”, facing the booster.
It seems to me that the sealing of the “GT3” model is much more logical !
Did you also found this difference on the 996 ? (or is this “typical” to the 986 ?)

Sorry for off topic, but for curiosity: a photo of my front brakes (sure, also PSS9) :

HTTP://SVC.EXAPHOTO.COM/EXAPHOTO/?T=...7C063CC87654B0

By the way, about nice and easy mods, a simple one to try to help to keep brakes as cold as possible is OEM GT2 air ducts.
Available as Porsche parts (number on the photo) cost about 30 bucks and real easy to install (replace much smaller ones) !

HTTP://SVC.EXAPHOTO.COM/EXAPHOTO/?T=...219B2E1C6FD5D7

..back on topic :

Btw, two comments :

a) Strange, on the list of cars, ..it do not says GT3 for the PMN166 !!!!

HTTP://SVC.EXAPHOTO.COM/EXAPHOTO/?T=...559FCD8E49AF44

b) It looks like “Brake Hoses Unlimited” on eBay has “THE” adapter :

HTTP://SVC.EXAPHOTO.COM/EXAPHOTO/?T=...A8EDB3C17CEF1F

Just curious, did you bench bleed the 997 master before installing in your car?

No I didn't. Just pressure bled with my Motive bleeder. No issues. Have done it that way three times now on two different cars with no problems.

Yes that looks like the perfect one. I searched all over and couldn't find one like that. Cool!

subbed.. this looks like a great option in my 99 C2..no PSM or anything, so I'm hoping it's an m12 front and rear port., I'll have to look at it after work... but with that adapter, either way is a breeze. 997 GT3 BMC is going on the list. Thanks for the how-to

A link would be nice - can't seem to find brake hoses unlimited on Ebay... Thx

Is this it?
http://www.ebaystores.com/BRAKE-HOSES-UNLIMITED

Adapter:
https://www.ebay.ca/itm/Brake-Line-T...UAAOSwZVJaxivb

Here is the seller I found:
https://www.ebay.ca/usr/goodbrakes?_...p2047675.l2559

This looks like the adapter, right?
https://www.ebay.com/itm/Brake-Line-...item4d353a6340

Just found this master cylinder on FVD Brombacher for $175.00 plus $15.00 shipping. Best price I have seen.

Sorry, you are right :
The easiest (on ebay) : eBay item number: 331605500736

The description line (title) is "Brake Line Thread Adapter, Male M12 x 1 Bubble, Female M10 x 1 Bubble"
and the vendor id is goodbrakes (14647 ) (100% Positive feedback)

I cannot wait ..to have REAL brake feeling on my 986 !
Thanks a lot for all the good info provided here.