I have Kooks with their cats, rest of exhaust is stock. I for one am not sure I would spend the money on headers for these cars until you have done everything else except camdhaftss (very last thing you want to spend money on). The exhaust really does not choke these engines like some people think they do.
No headers will not damage a stock engine or transmission but I'd do other things like a tune and 4:10s before headers. Just my opinion
Steven
2004 Marauder Black, loaded
Vortec S/C
4.10s
3500 PI Stall
Kook's headers
476.9 rwhp 385 lbs/tq
KVR's, QA1's, M&Z control arms, rear sway bar
Lidio tune
2004 Suburban Dark Charcoal
1970 W-30 442 convertible twilight Blue