Rover owners: Honda Civic Aerodeck 2.0i TD/ Rover 620 SDI max hp?

Hi ,
My name is Andreas, I´m from Austria and new on this forum so hello everybody

I currently drive a Honda Civic Aerodeck with the L-Series. It is similar with the 620 SDI. I read a lot on the L-Series and i´ve seen huge Power outputs on this engines(180HP and more) but only on the newer L-series cars like MG ZR,ZS and Rover 25,45 with the VP30 pump.

Especially today I´ve seen A Rover 25 with !original! GT1549 Turbo doing 180 whp on the Zeetech Facebook page .

I wanted to modify mine to reach about 170+ Hp. But I read that the VP37 isn´t good enough for that power output.
What I don´t understand is that the VW Guys also have the VP37 pump on their 1.9 TDÍ`s (AFN,ALH) but some of them reach with uprated nozzles, turbo, FMIC,etc. up to 200 HP. The VP37 on the 1.9 TDI(ALH) has a 10 mm Pump Head and they swap it for the bigger 11 mm of the AFN TDI´S to reach that massive outputs. If I am not wrong the VP37 on mine and on the SDI`s has a 11 mm Pump Head so i don´t understand why 170+HP are not possible for this pump.

So could anyone explain me the difference between their VP37 and the SDI VP37?

My list to reach 170HP:
GT2052V
Digibooster-S
Synergy VP
200 TDI nozzles
Water Methanol
Custom exhaust
Custom turbo piping
Uprated Clutch

In my opinion this mods will be good enough for 170+ Hp but as I said, I don´t know if the VP37 can deliver the needed fuel.

Hopefully some of you guys can help me

Greetings from Austria