I too, haven't ordered from CJ Pony Parts, but that's just solely because i know how amazing AM is! In the past, they have just about bent over backwards trying to help me with a silly issue. I dunno about everyone else, but my parts usually show up in 2 days, sometimes 3 from AM.
As far as one good bargaining-ship from CJ Pony Parts though, i like their installation videos better. I can see more of what's going on, and i'm a DIY guy, so I like to know what i'm buying and what i'm going to have to go through to get them on.
TLDR; passage here;
if you're curious to hear my story here it is:
I order some Magnapacks for a 98GT, the muffler hangers were welded 180į out upside down and backwards, which with a straight through muffler, doesn't technically matter. But every time i put the car on the lift, i see that the name is upside down and drove me nuts! the point is, i called AM and not only did they pay for all shipping, shipping old parts back, and new parts to me, they ALSO had magnaflow send the kit directly from their factory! and if that's not all, AM also provided me with an even further discount to my parts after the forum discount, i was able to apply another 6% off on my next purchase!! i <3 American Muscle
2015 Mustang GT Premium with Track Pack (i think calling it the performance package was just dumb)