I get good results with superdomes in my sons mk5, get the pistol head reduced by 1.5 mm and you will achieve 10fpe without spoiling it with a big spring. Scope wise a period 4x32 by kassnar or hunters for around 20 quid with do or up to date I've recently purchased a smk 3-9x40 for 18 quid off the bay that's ideal for the little gun.