I did the Alisport blank off [i[e on my Y reg TD5 Def 90 and i also took out the centre silencer and added a straight thru section. I then had STORM do a remap on my ECU and the motor flew afterwards. I simply couldnt believe the difference and was well happy. The pipe was NOT loud and passed MOT tests. On the Alisport pipe i used the connection provided for the old corrugated EGR pipe and left it in place so a visual MOT check looks like its all still in place and working.
Do these things on your TD5 and be amazed like i was..... oh and mine had done 180,000 miles!