Gunson Colortune question

[fizeus]

Hi all,
I'm new to the forum, so, at first I'd like to thank all the community.

I've read many discussions here, as a visitor, about the Gunson Colortune.
I'd like to buy to help my mechanic to fix the carbonation of my 2.4T (MY1973).
My carbs are the Zenith 40TIN and they are popping too much.

Is the colortune a good solution or can damage any part of the motor ?

My mechanic tryed to fix the carburation using the syncrometer but I think the mixtures should still be tuned.
Now I'd like to buy a colortune and on the Gunson site Gunson | Home but I see different models.

G4074 - Colortune Single Plug Kit
G4055A - Colortune / Hi-Gauge Adaptor Kit 10mm
G4055B - Colortune / Hi-Gauge Adaptor Kit 12mm
G4055C - Colortune Adaptor Kit 14mm - Taper Slim

Can someone please tell which product is the best solution for my Porsche ?
I know sparks are very distant from the cover and i 'd like to buy the right product.



Thankyou in advance for your help.