exhaust

["Mike Munson" <fasttrs@mindspring.com>]

Amici,
 
It is time for an exhaust system on the ITA TR6. The rules state that it
must exit behind the driver. The car has SS headers that reduce down to
2- 1.75 " pipes.
Should I go with a collector into a single 2.5 or 3"? 
Is mandrel bending worth the extra $?
What kind of racing muffler flows the best?
Thanks in advance.
Sadly I won't be able to go to  Mid-Ohio, my son is having surgery.
 
Mike Munson