This subject is mainly to let everyone know the difference between OEM and modified structure of exhaust pipe, as well as street car modified exhaust pipe(middle-tail part) will enhance power.We use original Luxgen U6 GT220(Taiwan brand) to compare the modified exhaust pipe and test drive.
The diameter increase on modified version apparently, the tube wall and metal joint are also thicken to increase strength. The catalyst in downpipe and the muffler in middle-tail part are by way of a straight(or with no catalyst ) to reduce obstruction of the exhaust.Most of modified exhaust pipe made of stainless steel and lighter than cast iron, if you want more lighter then titanium would be better and costs have gone up.
OEM exhaust head part made of cast iron to save time and cost, so the joint are thinner.The modified header can clearly see the exhaust manifold diameter has been increased and also redo the path to let the ignition sequence of each cylinder formed the emission will not cause obstruction in the flow pipe. The OEM catalyst in downpipe of metal box has high density like the 'block', cause the catback pressure is too large and underpower at high speed. The catalyst modified with 100-300 mesh density of metal box which the lower density make exhaust more smoothly.
To get close to the actual,we simulated instantaneous acceleration on road driving and get 30-80km/h, 80-120km/h, 30-120km/h range to measure time, G-force value and travel distance.We carried out at full throttle and without a fixed gear mode.Finally, the modified exhaust pipe overall performance street car is faster than OEM type on 1.01 seconds and shorten the travel distance of 14.48m which to cope with urban overtaking.
We found 'Thunder-Muffler' Taiwan manufacturer cooperated with this planning(combined with article and video) which attracting more than 100,000 hits on Option FB fanpage.
Article in testing results（Chinese ver.only）:
https://carnews.com/article/info/49fbd6ba-bab7-11e8-a9e3-42010af00004/ (Part1 and Part2)