You dont have to dis-assemble the front suspension
You can remove and replace the starter with out removing the header
You dont smash the header tubes on every bump.
The flanges are 3/8" thick so they dont leak and blow gaskets every other week.
The collectors actually line up with the cut outs in the cross member
You can get to the bolts
You dont melt the 5 and 7 spark plug wires on the #5 tube
Plenty of reason why TTIs are worth the money. People will spend thousands on building a car then stick the cheapest headers and converter they can on it. I dont understand it.