421 is wat u need......

It's ok...everyone has a start even those senior kaki used to be new too.

Since talking about extractor, 4-2-1 is better for street use 4-1 is for Mid to high rev usage but need to be reminded that not all will gain at high end with a 4-1 you need the valve to open higher during high revving. That's why you see VTec and Mivec they gain more at high end ith a 4-1 compare to those cars with valve lift system. For saga, it's better to just use a 4-2-1...I'm also running a SS 4-2-1 and find that my usagable rev range is wider now. Torque come in much earlier compare on stock. I have rev the engine just touching redline and the fuel cut kicks in. I'm still using my stock rear muffler as of now but the exhaust note has change after I change the extractor and the mid box. The note is still not loud and very quiet but has a bit more growl to it.

Just a info to share with al owners, if you change to a 4-2-1 the O2 sensor will be plug into 1 of the runners only. This is something I don't really like as the reading form the O2 will not be as accurate as reading from all the 4 runners. I've search around to change the O2 position myself to the down pipe after the 4 runners merge into a single one but got feedback that might caused the CEL to light up as longer the O2 wire, more resistance when the signal comes back to the ECU as the O2 sensor max volt is only 0.9V. Now the car is running a bit rich at higher RPM (it's a safety features from manufacturer to avoid pining and detonations)  as I can clearly hear a popping sound in the car when I release the throttle and when I shift at high RPM. but it's safer to run rich than lean as you won't risk blowing the engine but running more lean give the car a bit more power because the engine will run hotter.

when you change extractor, automatically your engine fuel consumption will be altered also, along with tons of other things such as exhaust gas velocity, pressure, etc etc.

I can't comment on FLX with 4-1 as I am using 4-2-1 all these while. My town driving economy actually improved. However, when I am cruising at highway at 140kph, fuel vanish faster compared to stock extractor.

Modification is all about trade off something to gain another. For my case, I trade off my high speed cruising economy for more city driving economy.

if you want to mod and puts low rev power as your main priority, then plonk in a 4-2-1 and you're all good to go.

Thanks V12Kompressor. Noted. 4-2-1 is the way to go. Mostly town driving so that would be my choice. Thanks again everyone for the input.

Is the torque curve that is been changed or moved that's why you have lower RPM reading compare to before. In stock form the engine rev has to be at 3000RPM @80km/h now after changing the header, you have moved the torque curve broader and lower hence your engine can work less to achieve 80km/h therefore you RPM reads lower. The gear ratio is still the same. What has changed is the torque output or the engine.