I don't claim to be some kind of engineer with expertise in this area, but I have done a LOT of reading and researching on many car forums over the years, as well as buying a very expensive and well made set of long tube headers for a previous car of mine -- so I wouldn't say I'm clueless either.

IMO, it's not even as simple as saying the headers will give you an HP and torque gain "when properly done", because I think much depends on the displacement of the engine in question too.

Time and time again, I've seen people try to put long tube headers on cars with 6 cylinder engines and fail to get good results. Meanwhile, it's almost always the guys with the larger V8's who have good things to say about them.

Especially on a lot of the foreign sports cars out there like the Hyundai Genesis Coupe or some of the Nissans, long tube headers wind up generating a lot of "rasp" under acceleration too. It's just not a generally desirable exhaust note at all.

I'd love to see the dyno before and after results for these headers for the Crossfire, and I'm far from being the guy who would definitively tell you they "won't deliver results". But count me skeptical, based on past results I've observed.

These are a labor intensive and expensive modification to make for relatively little gain, too -- even if they're a success. I doubt I'd ever put long tubes on another vehicle of my own.