dare i say overboost problem?

howdy folks, finally got my d2 perfect, slick gear change due to every bit of oil everywhere being changed and ive had the ecu autologic remapped which made a noticeable difference on the drive home but then changing the exhaust for a decat no centre box one, removing the EGR and putting in a K+N panel filter has truely unleashed its potential. if youve not done it. do it. its the car it should have been, no more stirring the gears all day and it pulls from 1500 rpm. 1000 miles in a week and i finally love my disco (aaaaaaaah) one fly in the ointment is at exactly 3500 rpm under heavy acceleration it loses performance, turn it off an on and its good to go. suspected overboost as my galaxy did the same thing, had it checked on the autologic fault reader, sure enough overboost. it didnt do it before but as they are so choked by egr/cat etc it probably couldnt muster the huff. ive read lots of maybe this/maybe that stuff on here but i have to ask has anyone who's done the same sort of mods had exactly the same problem? im going to check the waste gate over the next few days and the chap at the garage said the same thing but he also said the egr removal may have 'pushed it over the edge' i could put it back on and try it but i dont really want to go back to the bad old days. any advice gratefully received.

Check MAP sensor and get a decent boost gauge to check pressure.

Id normaly say the actuator... but If its specific to a rpm id say your remap is the fault. You should do all this sort of thing one at a time. Not all at one go