Hey, I am looking for some recommendations on some coils and spark plugs for my 2008 Civic Si Coupe. I am looking to add some horsepower if possible. The only modification I have done currently is a K&N Cold Air Intake.

I am looking at getting some headers, and a full exhaust system as well. The issue that I am running into is that most of the places that I have researched some sights, and it seems like they are only doing cat back kits. I would like to have a full exhaust from the headers back, and then later down the road replace the headers. In addition, I have heard that with an exhaust system, that defowlers may have to be used due to the O2 sensors. Is this true?

Essentially what I am looking at doing is to increase power and performance over sound. I have heard good things about Magna Flow, and Borla. If you guys can help, that would be awesome!

 

stick with oem for coils and plugs, unless you are putting down serious numbers you don't need to do a single thing other than replacing your plugs more frequently, if needed. as for exhaust manifolds, the aftermarket ones typically replace your cat, considering the cat is built into the stock exhaust manifold and this would involve a CEL unless the secondary defouler trick works, can't confirm or deny it. but DC makes a manifold (although i don't like it much) so does skunk 2, hytech etc, all this was revealed by a quick ebay search for "2008 si header"

as for power gains? Kpro and a good tune will do you worlds of good, aswell as the ability to disable your secondary 02.

 

i got a strup header and skunk 2 cat back on my car. i like it. its loud as hell though in vtec, wich turns some people away from it. you will need the defouler or you will pop a cel. i ran into this issue when i did my install. but its an inexpensive fix. corsport.com sells the defoulers. if you put a defouler on you may wanna extend the wires for the o2 sensor. it seemed to put a lil to much stress on the wires when i put mine on due to moving the sensor a lil farther away. also, the defouler will help you pass emissions test if your state has em as long as they test through the obdII port. if they rod the exhaust for the test it will fail. you will need to get cat put on. from what ive seen vibrant is the only company that is producing a header with a high-flow cat option. hope this helps.