Uhm, safety should be a motto that we all take.
Most seats are tested for 'head-on collision' what happens when some 4000lb mustang piloted by some drunk a-hole smacks your stationary car at 40mph while you're still in it? your $150-$200 seat will crack, and I would not let my spine be in danger, the extra $200 per seat is worth your life! Mugen (IMO) makes the best seats for honda, due to their extensive testing and race-proven technology. But I am 100% sure that Sparco, MOMO, Recaro designs are a hell of a lot safer than stock seats which OBX or Ten-R can't even compare to.
SAFETY FIRST!!
and a lesson learned by myself: A deal is good, its cheap it good.. Now it has 2 meanings, if they advertise a design without dyno or safety to back it up, it must be let go, spend the extra $100-$400 and get a good name: HKS, Skunk2, Greddy are the ones I've seen toss great performance from a cat-back, DC-Sports are well known for header systems, AEM.. by far should take care of your intake, accept nothing less if you want performance.
and remember this:
IF YOU WONT PUT CHEAP OIL IN YOUR MOTOR, WHY WOULD YOU PUT CHEAP PARTS ON YOUR CAR?!