I think the true test with these elbows is the difference in BHP V's increases in boost.
I mean, when I had a standard elbow and turbo, at 1 Bar I got (Can't remember exactly but IIRC) 290BHP, 1.2 Bar 310BHP, 1.4 Bar 315BHP.
With a 3" elbow & downpipe I got, 1 Bar 310BHP, 1.2 325BHP, 1.4 Bar...