I have dealt with X-Force exhausts in the past.
I cannot recommend them enough. They are simply VALUE for money. You get Japanese craftsmanship at Chinese goods prices.
Apparently the exhausts with mufflers that are robotic tig welded (N1 style mufflers) are made at the same factory that HKS source out their exhausts to get made. Surprise surprise HKS dont actually make their exhaust systems. They are subcontracted to a factory that makes them. XForce is run by Malaysians (I think) but the actual products are made in Japan. Note, I dont think the whole XForce line up is made in Japan. However, it is quite obvious which ones are the real deal and which ones are cheap crap.
If you go the the xforce website, the Thunderball mufflers are the ones made in Japan. I wouldnt buy an oval muffler.... basically the mufflers that show the robotic tig welds are a safe bet, whereas the mufflers that have had the welds linished out are probably not made in Japan (prob china).
As for full exhaust systems, the WRX and 200sx systems are made in Japan. They are as good as HKS exhausts. Mandrel bent (no weld tags inside like with custom jobs). Looking at the Skyline exhaust, that looks like a good buy.
Im also pretty sure that the turbo manifolds and extractors are made int he same Japanese factory.... just look at the photos... simply amazing quality.
Dont hesitate to buy, $970 is a steal. you are basically buying it a fraction above trade price. However, the skyline exhaust might be pretty loud as it uses a hotdog style resonator, whereas the 200sx uses a secondary muffler and has a very quiet/nice exhaust note.
BTW, i dont have any bias as there is no financial incentive for me. I just think they are the best value for money exhaust going around. you will not be disappointed and dont be so anally retentive :Pimp2: