You guys are all wrong. First of all, DC does TONS of R&D on their headers - they tune aspects like runner length, tubing size, and harmonic resonance (to improve vacuum for sucking gases out of the head). They also have better quality build and materials than Megan. They have been dyno proven time and time again to provide solid gains - even in the Import Tuner power pages tests and Sport Compact Car tests. Most of DC's headers are designed for street use, so they don't produce massive peak power gains like other headers. However, DC headers (especially the 4-2-1) make consistent 3-5 hp gains throughout the entire power band. In reality - especially for a street car - this is much more valuable than peak power in terms of function. Dyno queens not welcome :lol:
Megan Racing products are garbage. I've installed three Megan Racing headers and two of their test pipes on friend's cars. All three of the headers leaked from the stock gaskets, all had thin metal and shoddy welds. One of them actually cracked at a few of the welds over a very short period of time.
Both of the test pipes I installed along with the headers cracked and leaked at the welds within one week of use. My guess is that the materials they use can't handle the heat of the exhaust. On top of that, the fact that every single one leaked at the gaskets denotes a major flaw in the manufacturing process.
Also, there is little to no proof that the Megan headers will dyno with good gains, and the fact that they can't handle heat will severely dampen their effect long-term even IF they manage to make one or two good pulls.