Had a look on SuperGT.net to see what the go was with the Xanavi NISMO GT-R after it's strong initial start to the year ...

Round 1 - Suzuka
- 1st
- No weight penalties
- http://supergt.net/supergt/2008/0801/0801race.htm

Round 2 - Okayama
- 1st
- 50kg weight penalty
- http://supergt.net/supergt/2008/0802/0802race.htm

Round 3 - Fuji
- 14th
- 115kg weight penalty
- http://supergt.net/supergt/2008/0803/0803race.htm

Round 4 - Malaysia
- 13th
- 95kg weight penalty
- http://supergt.net/supergt/2008/0804/0804race.htm

Round 5 - Sugo
- 14th
- 75kg weight penalty
- http://supergt.net/supergt/2008/0805/0805race.htm

The worst any competing GT500 team has received was a 60kg penalty the PETRONAS TOM'S SC430 was handed in round 4.

The heaviest any NSX team has received was the last round at Sugo with a 50kg penalty; otherwise they've carried only 30kg on average if at all.

I think the weight penalties have gone a bit screwy this year after the initial shock of the GT-R running so well in the first two rounds and the 115kg weight penalty was a knee jerk reaction to this.