There's a set of both long tube and shorty headers out from Pacemaker (an AU company). The shorties will fit. The LTs may not.
And the Baer 14 inch/6 piston brakes for the G8 should fit, as dragoneye pointed out. I called them and they confirmed that they will fit under 18 inch wheels, so no stock wheels should pose a problem.
- Xanthos
P.S. - Pricing for the headers is 505.00 for the LTs and 440.00 for the shorties. Pricing for the brakes is 1895 for the front, and the same for the back. Those are the two important ones. I'll keep you posted though.