hi bro ,all these are right about to increase ur HP,what all my respected fellows 4got to tell is about ur own safety.if ur putting in some raw power under ur hood then u must have a raw way to stop it or u'll end up with ur car in someone eles's rear bumper or might could be the wall.ryt get high compund brake pads,abs system if possible if not then just 4wheel disc brakes get of the bulky gas cylinder,if u want to use gas n still get the same performance .hit me here's my num i'll trick ur ride with cng on it but still u have to get smaller cylinders 4 of them would give u the quantity for enough gas but they will be lighter in weight.
along with high flow headers,down pipe.ur uppipe should also be restriction free,get a greddy air intake with HKS ssq BOV,get a certified exhaust(means something like HKS,GREDDY,INJEN,BUDDYCLUB,5ZIEGEN ETC)
4tip irridium tip or platinum tips are necessary as they would give a stronger spark to light up and burn all the air fuel mixture cz with larger air induction u need a higher voltage to utelize it all,
go for a polished heads,intake manifold etc,get a fuel pump BOSCH 10V would be fair enough,get a custom fuel feed,(aka fuel rail),high flow injectors,adjustable cam gears,forged pistons,light weight crower cam,light weight Fly Wheel,Axis's LSD.n so on n on bla bla.hehe
here's my num i live in lahore hope u would like to go on a race with me