I've got the Hiteq springs on my car (with standard shocks), they are a 40mm+ drop and with the standard shocks suit the car very well.
You say you can't afford to lower the car properly using coilovers, well I've also been down that road and had a set of JIC coilovers, and yes they did improve the handling as long as you were on a PERFECTLY smooth road, sadly though on good old british, bang crash pot holed wrong camber rubbish roads, they actually made the car worse to drive. You couldn't drive fast as you were constantly looking for the next pothole or stone in the road. So having the coilovers on is great if you like driving slow because you feel like the car is going to fall to bits every time you drive over an unsuspecting ant. As far as I'm concerned coilovers are great for track days but crap and total waste of money for road use.
Perhaps if you did buy the Hiteq springs and wanted to try out an after market shock, the GAB shocks are rated very highly or you could try the all new Whiteline shocks which have just recently been introduced for the Pulsar.
S