See below cut and paste from another thread. You can find similar performance for less from NZ and Aussie makers with a HansO free tune download, Commander IV with or w/o an Auto tune do some searchs and read a lot of threads. Helpfully the forum provides similar related threads posted at the bottom of threads to get you started.
For US you will have to go Carpenter or for International go here:
New Zealand - Viking Exhausts and a forum member
@Paul Bryant
Forum thread -
Paul Bryant Headers!
Australian - CES
Home-Custom Exhaust Specialists-CES
Forum thread - CES ****
or Reband
Reband <br />Motorcycle Exhaust & Classic Bike SpecialistS
Forum thread - use your search function these were developed with the assistance of famed Aussie tuner Neville Lush who is also a forum member so add 'Lush' to your search