Welsh native speakers would certainly mutate the words you mention, as they would other English words. For example, in Caernarfon, a town where I spent many happy Saturday nights as a boy, I am sure that you would(today) hear the following dialogue; 'Wt tisho chips efo dy gyrri?'(Do you want chips with your curry?) or, the converse: 'Wt tisho cyrri efo dy jips?'. Moving away from food, consider the following sentence: 'Wyt ti wedi cael disc caled ar dy gomputer eto?'(Have you got a hard disc for your computer yet?) or, 'Lle ddaru ti brynu dy ddisc caled?' (Where did you buy your hard disc?). Thes words were used by a colleague and myself a few weeks ago. John Williams, Saudi Arabia