TTI vs Hedman which one?

OK folks,
Right now I have a 440 in my 71 Dart with 727 and Schumacher headers. I am working on building a 451 (B) motor with a Powerglide. The 451 will have Victor heads. My dilemma is I need headers that build power, don't drag and and can swap between RB and B motors. I have been looking at TTI 2" and Hedman fender wells, both seem to have there pros and cons.

Here is what see:

TTI / Hedman
Both same price for bare headers
Both fit

TTI's - Dont build as much power???
TTI - can have coated at shop - more money
TTI - Tighter fit?

Hedman - Need to cut fenders
Hedman - More power?
Hedman - Easier install?

This car is a street/strip car, not going to be a restorer (Mini-tub, spring relocation)

Do you have pictures, insight, issues you worked through??

Any suggestions -
TTI: http://www.ttiexhaust.com/Header-TTI440-200/BB2headers.htm

Hedman: http://www.summitracing.com/parts/hed-75160/overview/make/dodge/model/dart/year/1971

Thanks
CP