That seems a bit odd...you want to replace them but dont want the handling affected? Just get the Renault springs then! Am I missing something here?
How exactly do you mean uprated? More poundage or something? In that case, no I dont know the original spring rating...but to get to my point what is your reason for wanting uprated springs (by which I assume you want to stiffen up the ride and improve the overall handling)?
A slight drop on harder springs especially if you can get progressively wound ones, will do what you want. Doesnt make much sense to just get harder springs but keep your centre of gravity the same...if you want a hard ride, just get some poly bushes.