I think it´s time for me to chime in.
"chime"
Got the mentioned 261 with the x-pipe and the dyno proofn 8%.
Jim is right whe he says that on a stock 6 there will be no big differenc.
My 261 is pretty warmed up and it made a difference. Period.
My exhaust guy (an 70 year old hand with log time racing experiance) did a normal split setup first.
Than he sprayed the tubes from the headers to the mufflers with a can and drove the car real hard.
He inserts the x at the first location where the paint was not burned off from exhaust heat.
He told me, that he got that trick from his teacher, who was involved building the famous german Autounion racing cars before WWII.
What can I say? It works for me.
Frank
