MAC header concerns

[Shotgun28]

Okay well I just got my new gt40 P heads and from my understanding from calling and emailing companies, the only long tube that will work on the P heads. But is it just my imagination, or is there alot of MAC bashing in here, and I am wondering and nervous to get these, but I already have the long tube h-pipe, and I would rather not replace both the headers and the h-pipe.Could you tell me why they are bad, and what the concerns are when stating they are "crap". Thank you.

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91 LX Convertible Gray on Red B&M Shift improver kit,ASP red alum. underdrive pulleys, Richmond 3.73 gears, 1 5/8 Flowtech long tube Headers and off road h-pipe, Flowmaster 2-chamber cat-back with S.S exhaust, MSD 6A Ignition with coil,Cap and rotor, Taylor Pro wires, K&N 12" conical filter system, Jet stage 2 performance chip and just purchased some GT40P heads, looking at exhaust, Lentech Street Terminator plus on it's way...