Here's about as good a breakdown as I can make away from home:
Stock Cats
High Flow Cats (HFC's)
- Either Ceramic or Metallic Core - You'll want Ceramic, last longer, least prone to core ruptures
- Better flow than stock cats, but less than test pipes or headers
- 50/50 chance of passing sniffer tests
- Still retain 'Stock' look for visual tests
- Mild HP/TQ gain
(Resonated) Test Pipes
- No Cat whatsoever
- Will NOT pass sniffer tests
- Better flow than Stock/HFCs, but less cleanly than headers or ART pipes
- Resonated TPs will have less rasp/drone than Non-Res but performance is unaffected
- Moderate HP/TQ gain
Advanced Resonance Test Pipes (ART Pipes)
- No Cat whatsoever
- Will NOT pass sniffer tests
- Improved flow over regular (R)TP's
- Slightly nulled rasp, but still noticeable
- Slightly more HP/TQ output than regular (R)TP's
Long Tube Headers (LTH's)
- Sex
- As with (R)TPs and ART Pipes, no cat whatsoever
- Smoother flow than all previously mentioned parts
- Distinctive sound, slightly higher pitched yet quieter idle
- Most Dyno proven gains out of the group.
- Hardest Install of the bunch, but looks the best when completed.
Hope this helps with the basic idea.
