Do you need to chip ps2 ?

[penz]

Can any one help answer this question ....is chipping really needed to play back ups ....i dont want to get my ps2 chipped yet cause it still has it's warrenty and by chipping this kinda wipes this out ......is there any other way ? ie gameshark 2 etc....is there a swap disc trick and if so how is it done.....any advice would be great.....i dont want to play imports just straight back ups of pal games...thanks penz