we have a stream here at the garage its auto i wonder why it comes with a 4-1 header

jdm d17a vtec

 

What exactly are you asking?

Yes, they come (stock) with an exhaust manifold that has four individual pipes (one from each exhaust port) and they come together at the flange.


Why? Because they're not built with the catalytic converter on the manifold, like the LX/DX D17A1 engines.


Edit: It's also for more efficient exhaust flow. The log-style exhaust manifolds that you may find on some vehicles simply do not flow well. Each exhaust port ends up flowing into a single chamber before it has a chance to escape through the system. With the design of the D17A2 exhaust manifold, each exhaust port has it's own pipe for the exhaust gas to escape through before it enters the rest of the exhaust system. It just works better this way.

 

ok boss