I need to raise the ride height on my Octy estate, the under tray keeps catching speed bumps that are only 3 to 4 inches high

Have you checked to see if the under tray is loose or hanging down?

I don't recall ever catching the under tray on my Octavia when negotiating speed bumps.

Raising the ride height can have a serious impact on the handling and safety of the car if not done correctly.

I need to raise the ride height on my Octy estate, the under tray keeps catching speed bumps that are only 3 to 4 inches high

In Skodaforum.nl, a lot of members do complain about that problem. There, some plastic parts are put in the springs at the back, so that the car doesn't hit the road any longer on road bumps. This might illustrate what I mean: http://www.niveauplus.nl/levelplus/producten/4/1315_kunststofringen_2_stuks/

The advantage over new and stiffer springs would be that the behaviour of the car doesn't change at all, the suspension just can't go that deep as before.

In Skodaforum.nl, a lot of members do complain about that problem. There, some plastic parts are put in the springs at the back, so that the car doesn't hit the road any longer on road bumps. This might illustrate what I mean: http://www.niveauplus.nl/levelplus/producten/4/1315_kunststofringen_2_stuks/

The advantage over new and stiffer springs would be that the behaviour of the car doesn't change at all, the suspension just can't go that deep as before.

Thanks for the link

I only need to raise it about 2 inches, many years ago I had a Nissan sunny and obtained some struts that you could raise or lower just by using a small tyre foot pump

Is there any longer struts, and rear shockers that may help available from somewhere

I recommend buying a Scout