Hi schwaz80,
While there are too many unknowns, variables, and personal preferences involved to make any specific suggestions … post #2 here and the topper guidelines it links to has more information that can help you use your sleeping experience on a mattress as a reference point and guideline to help you choose the type, thickness, and firmness for a topper that has the best chance of resolving any “symptoms” or discomfort you may be having on your Sultan engenes and includes a link to a list of the better online topper sources I’m aware of as well.
Phoenix