Factory is 2-bolt and a better option anyway. It allows you many different upgrade options in the future from the many manufacturers that make stock mounting parts. My Full-Race EFR kit is a 2-bolt to the header.Is the factory up pipe a 2-bolt design? I'm asking because Killer B has a 2-bolt option, but I'm not sure if that means it works with my factory up pipe.
The reasons I'm not considering the more expensive option with their own up pipe is because my tuner says installing the up pipe adds considerable time to the install and there's not really much benefit other than looking prettier...and it's more expensive.
I've NEVER liked the V-band option on the KillerB.