Ok, here a few facts:
The system is completely made in Italy. A LOT of JDM parts are made in Taiwan or China (HJS, Invidia, Tanabe etc) so they are cheap, and I have to be honest, (sometimes) they are well made, as the workers are very cheap they can afford to have more people, for example you can have a single worker that makes the same TIG welding on the same part all day long...
They usually are too loud in full system form, and the headers are often nice looking but fragile.
Anyway, the price of 6k is just an indication, based on the cost of similar system from Superprint, for example the GT3 system has step-design headers, HJS 200 CPSI cat and a rear exaust with black tips...it made 465 Hp on the mk2 3.8, that had 446 hp from standard, and that's on a higly strung NA engine, JUST with the exhaust...and it's around 7k.
I have no idea whatsoever what this system could do on a SC car, as the headers are a lot bigger (we're talking 42mm for the first ~150 mm, 48 for the rest of the primary pipes, with soft variations between..how big are the F.I.?), and the cats are the best in the world!
Another thing, how much is a new 370Z in the US? because here in Italy it's 41.000 Euros-->58,000 USD for the Coupè.
Consider just this, the previous full system developed was for the Mercedes SLS AMG (that's a 190k Euros car!), and it was made with the same philosophy. I've seen the dyno charts: standard car 581 HP and 640 nm. Full Exhaust 603 HP and 700 nm..but that's not the full story as at 3800 rpm there was a 55 hp increase! Hamann is going to offer this system in his catalogue (Supersprint makes all the system for Hamann, Hartge, Carlsson, Lorinser, Geiger, Techart, AC Schnitzer etc...)
Here you can watch all the recent cars, SLS included:
YouTube - ‪Supersprintcom's Channel‬‏