Welp, yet another season is over and it's time to do more to the Civic. I need a little help from you all in choosing the type of header best suited to my car/class.

The car is a 2000 Civic Si with 102k. It runs in STS and just won that class here in San Antonio (WOOT!).

So what would be the best type of header? 4-2-1 or 4-1? Keep in mind the car has a B16 so low end torque is always welcome.


Thanks in advance!

Kevin


PS - While you're at it, if you all have ideas on the rest of the exhaust system it would be most apreciated

 

Since you're in STS, your header options are limited. I'd just get a cheap DC 4-2-1 and forget about it because until you can change that tiny collector you're not going to see the kind of midrange gains you're probably looking for. Asking for more low-end torque is pointless and irrelevant, you're never ever going to be below 4k rpm unless you screw up (seriously, don't bother trying). As for the rest of the exhaust, I'd just run a 2.25" or 2.5" custom setup with a resonator and a muffler that can be removed easily, depending on how much noise you can stand.

Actually, if it were me I'd go to STX, ditch the cat for a 2.5" and then spend a whole lot more money on the header.

 

What are you allowed? Keep stock size collector or 2.5"? Stock cat? Aftermarket? Test Pipe? Any exhaust? Exit at the rear of car?

 

According to Moutons (I know, not totally perfect so if this is wrong please tell me):


From the engine back I am free to do what I want as long as it's emissions legal. I would assume that means I can put a high flow cat and any diameter I want for piping. I would also assume that it has to exit behind the driver. Please let me know if this is wrong though. I'm waiting for the '05 rulebook (lost the '04 in a move) so I can't check it.

 

You still need to be emissions legal in STS and STX, not sure why you think you can get rid of the catalytic convertor. You have to go to street prepared to take out the cat.

 

Did you read my post? No high-flow cats allowed in STS. The header is free as long as it collects in the stock cat and the exhaust behind the stock cat is free. The factory cat must remain unmodified and in its original position. STX allows high-flow cats within 6" of the original position.

 

Rich,

That's what I thought but Moutons didn't say it so i wanted clarification.

Thanks for your help. DC 4-2-1 it is then.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EtherGhost &raquo;</TD></TR><TR><TD CLASS="quote">You still need to be emissions legal in STS and STX, not sure why you think you can get rid of the catalytic converter. You have to go to street prepared to take out the cat.</TD></TR></TABLE>

I didn't think that. If you read my post I was merely asking if any of the items I listed were legal.

From what the STS rules sound like I would run a DC 4-1, GReddy or APEXi. If you wanted to get serious, have one of the custom header manufacturers make header for you, but not sure what gains you will see with a 2" collector and stock length, but if you want to exploit the rules to the fullest...

For exhaust I'd probably just do a KTeller 2.5" or similar.