This is a question that can normally only be answered by the developers of SimBin.
According to the GTL manual Perran Truran was the leader of car modelling.
But another idea:
Why don't you ask the guys who did the Ferrari 250 GT SWB if they can do an extra exhaust version for the 275 GTB 'cause this modell has got the four rear waste pipes.
http://www.kcendra.com/nfsbolide/nfscars.php?
name=250swb&game=gtl
There's a link to "Butch" down on this site.
If this doesn't work we can put up posts on the well known GTL sites if somebody is able and willing to do something like this.
Regards Mental