Extractor 4-2-1 or 4-1?

In my opinion it's best to opt 4-2-1 for street use and 4-1 for track/circuit use. 4-2-1 will give the car all-round good power and 4-1 will sacrifice the low end power to give the best power at higher rev. Now, let's discuss about the design when choosing the extractors. For 4-2-1 extractors, all the pipes should be in equal length compared to it's partners, it's easy to say but hard to do so we should pay extra attention to this issue. The length of each pipes is also critical to where and how much power we'll get, longer pipes will give better pick ups and vice versa.