gtv6capri
Essentially the 165 HP cars used the early 3000E driveline.  "D" shaped inlet ports gave better flow, Pistons were slightly higher compression, and the camshaft profile was improved slightly.  Also the later UK spec cars had a viscous coupling fan.

I think this explains it.

Were the stickers produced by Ford or the dealer?  Surely if Ford made them they would have put the Ford logo on it.
 
This is from wiki
 
one of the first 50 engines which was in a RS 3100 that was free for car magazines to review and test in fact had 165 hp (123 kW; 167 PS) instead of the 148 hp (110 kW; 150 PS) of the rest of road going RS 3100s....
 
Also Jeremy Waltons book states pre production RS3100 had 165HP due to cam and exhaust mods and that these mods were expensive and never made it into production, and that the RS3100 was quoted at 148HP, page 58.
 
So maybe the dealer made the stickers and maybe they got the 165 figure from a review of an RS3100 thinking that it was the same engine??? 
 
If we use consistent units then I think its safe to say that the early capris were 128HP, the RS3100 was 148HP and the BSS were up to 138HP depending on if all the mods were included such as weber 38DGAS and viscous fan.
 
In any case it's highly unlikely that they were a genuine 165HP.
 
 

I have the Capri owners handbook, complete with the yellow sticker from when I owned one of these.
There's no Ford logo on the sticker.
 
Full wording is:
 
SPECIAL VEHICLE
Your CAPRI is fitted
with an uprated
V6 165 B.H.P. motor
and associated components.
It is essential
you identify as such
when ordering
replacement parts
through your FORD dealer

The yellow stickers were indeed Ford sanctioned. They were to help identify the cars so dealers could fit appropriate spare parts as necessary at service.
 
        Engine power is one thing but it was the gearing changes that made a huge difference to performance. Even with the rs3100 I would suggest that the ventilated front brakes did as much or more for overall performance as the extra horses.

gtv6capri
Deano does the car still exist?
 

yes,I have kept a few of the options from it, but the car has been resto'd by a local Capri collector, and is just about completed as far as I know.
Its had alot spent on it, more than I could afford when I was younger anyhow.
Funny, I checked the service book the other day, and the car was sold new here in Geelong, and it's spent all of its life within about 50k radius.
 

Hi Ron, will get the OM out again.
It was sold to an engineering firm in North Shore (Geelong).
Will Pm the s/n to you and further details.

My guess is 32747.