Hi all sifu, sorry if my question had been ask before .

I currently driving a iswara aeroback with 4g91 EFI , Current exhaus set up is .

- Open pod intake
- 4g93 Dohc extractor header , but 2-1 using mivec
- 2 inch paiping from front to rear follow the original paiping bending way
- Center swirl bullet
- Marco S-flow muffler

Now my top speed only maintain at 150 , how to make it more ?

Before that is using standard iswara paiping with 2 swirl center bullet and also the marco s-flow, simply can go to 180 . Now after change to 1 center bullet and 2 inch paiping . My top speed drop .

With the latest setup up , the exhaust sound abit too bissing . I am planning to change away the muffler , hope to get back the top speed. I more like top speed rather then pick up as i use highway daily to work .

Please give some advice . TQ . S-flow , straight or twin loop ???