Taken from this site:
http://www.dohc-vtec.net/pages/linke...udm-vs-jdm.htm
Weight Gain (compared to VTiR)
Stiffer Suspension/High-grip tires +5.500kg
LSD +1.500kg
Performance Rod & Aluminum Make +3.440kg
Body Stiffening Metal Sheets +1.711kg
Strengthening Wheel Bolts & Bearings +0.704kg
Strengthening Tailgate Area +0.313kg
Stiffer Rubber Exhaust Piping Mounts +0.140kg
Recaro Seats +6.647kg
Front Spoiler +1.034kg
Rear Spoiler +2.900kg
Miscellaneous +1.160kg
Total Increase: +25.049kg
so it's not that much heavier.