You might have the following standard ride height rear springs:
5Q0511121AF (Standard Ride Height Octavia MK3 Estate Rear Springs
Wire Diameter: 11.25mm
Length: 341mm
Outer Diameter: 109mm
Weight: 1.75kg
Number of Coil Turns: 7.75
https://web.tecalliance.net/gkn/en/parts/1/87783/detail?query=5Q0511121AF&numberType=1&oe=5Q0511121AF&groups=188#@brc/search:Search%20by%20any%20number%205Q0511121AF;query:5Q0511121AF;groups:188;brands:1;page:0/detail:87783;brandId:1;articleNo:87783;query:5Q0511121AF;numberType:1;oe:5Q0511121AF;groups:188
To increase the rear ride height by 15mm change to the following 15mm increased ride height rear springs:
5Q0511121BE (15mm Increased Ride Height Octavia MK3 Estate Rear Springs)
Wire Diameter: 11.25mm
Length: 356mm
Outer Diameter: 107mm
Weight: 1.75kg
Number of Coil Turns: 7.75
https://web.tecalliance.net/gkn/en/parts/1/88024/detail?query=5Q0511121BE&numberType=1&oe=5Q0511121BE&groups=188#@brc/search:Search%20by%20any%20number%205Q0511121BE;query:5Q0511121BE;groups:188;brands:1;page:0/detail:88024;brandId:1;articleNo:88024;query:5Q0511121BE;numberType:1;oe:5Q0511121BE;groups:188
5Q0511121BE Suplex 30026
https://www.autodoc.co.uk/suplex/15518365
This is a very neat solution, as the specifications of the springs are identical, except for the 15mm increased uncompressed spring length of the increased ride height rear springs. The ride comfort will be exactly the same. You will now have 15mm more suspension travel. This could be useful if the standard suspension sometimes bottoms out, for example going over speed hump. Increased ride height isn't for everyone, because it raises the car's centre of gravity. However, SUVs are very popular and they also have a higher centre of gravity than standard road cars.
There's not much choice for 5Q0511121BE rear springs, although autodoc list Suplex 30026 that matches this OEM part number. Other brands are sometimes sold to replace more than one OEM number, so might not be a close match. Those one size fits all approach springs are best avoided if there's another alternative. Some brands hide the fact that they are using a one size fits all approach by listing just one OEM part number against each model number...but what they are doing is labelling the same spring using different model numbers....Caveat Emptor...as they say in Latin. These one size fits all brands, tend not to list the specification of each spring, such as wire thickness, length, outside diameter, etc.
There are 9 standard ride height Octavia MK3 rear springs listed on the Skoda online parts catalogue
1
5Q0511121AA
coil spring
Model data: PR-1JA+0YA
(1)
5Q0511121AB
coil spring
Model data: PR-1JA+0YB
(1)
5Q0511121AC
coil spring
Model data: PR-1JA+0YC
(1)
5Q0511121AD
coil spring
Model data: PR-1JA+0YD
(1)
5Q0511121AE
coil spring
Model data: PR-1JA+0YE
(1)
5Q0511121AF
coil spring
Model data: PR-1JA+0YF
(1)
5Q0511121AG
coil spring
Model data: PR-1JA+0YG
(1)
5Q0511121AH
coil spring
Model data: PR-1JA+0YH
(1)
5Q0511121AJ
coil spring
Model data: PR-1JA+0YJ
http://www.oemepc.com/skoda/part_single/catalog/sk/markt/CZ/modell/OCT/year/2016/drive_standart/753/hg_ug/511/subcategory/511000/part_id/0/lang/e
In some countries, new car buyers have a 15mm increased ride height option. In other countries (particularly those countries with poor roads and lots of potholes), the 15mm increased ride height will come as standard. So +15mm ride height, standard ride height, and -15mm (lowered suspension) options are all perfectly normal on VW group cars.
It's easier to change rear springs than front springs, so do them first. If all goes well, repeat the process on the front...again using suitable springs.
The Scout springs appear to heavier duty and much longer than the +15mm increased ride height springs. So it might not be a good idea to use Scout springs on the standard car. Besides, +15mm should be enough for most owners who want a small increase in ride height.
In the UK, there is a lot less choice (and sometimes higher prices) for increased ride height springs compared to standard ride height springs, so do check availability first before making a decision to go for increased ride height springs.