Well,

First, I have to ask why the booster pack cars (Veyron, Gallardo Superleggera) cost 0 in career mode. I do not understand this. They should at least be locked until Showdown:Autopolis is finished.

Also, I wonder if EA was considering making another booster pack with some new tracks and cars like the S7, SLR, others. It seems that ProStreet is very much alive. I'd buy it fa'sho.

Do these cars come out when you install the booster pack or once u reach a certain percentage in the game? i want to buy the veyron but don't know where.

First, don't revive threads. This was old. Anyway, the DB9, Gallardo Superleggera come in 2 $10 booster packs which you buy from PSN Store, Xbox Live Marketplace, or whatever the PC thing is. The Veyron and F1 come seperately for $2 each.