I have been looking into headers recently for a buddy of mine. Ws6 with full bolt ons and dominator 2 camshaft. He's planning on adding heads and possibly forced induction. Looking for some opinions. 1 3/4 I hear is good for full bolt ons while 1 7/8 for higher cubic inch motors or forced induction. I'm sure this has been beaten to death.. what would you do? he already has kooks 1 3/4 headers , is it necessary to go to the 1 7/8?

 

I would definitely get the bigger primary headers. Full exhaust was the first mod I did on my car and I had big plans for the future so I went ahead and got 1 7/8 headers. I'm sure the smaller ones would have worked but there's no sense in buying something you're just going to have to replace down the road.

 

If he already has the 1 3/4 headers I would just keep them. The bigger headers might help but is it worth the cost/labor?

 

I agree!

 

1 7/8 we are done

 

Keep the 1-3/4 if he has them and they are installed. He is leaving potentially 10-20rwhp on the table NA and even more boosted.

We need a giant sticky in neon flashing letters: 1-7/8 or 2" headers for my car? 1-7/8" would be the choice for stock/bolt-on, heads/cam, small boost, and smaller strokers while 2" is better for big cubes and big FI. 1-3/4 isn't worth it.

 

Really tempted to put 2" headers on my 346 when it's nitrous powered.

 

If he does the install himself and sells the old ones he won't be out much or any money depending on which brand he gets.

 

Well put! This topic has been beaten to death. If people did a little bit more digging they might just find the answers to their questions.

 

You might want to change that to 1 78's for most builds and 2" for FI and REALLY big cubes. This guy lost tons of low end TQ and only gained 1hp going from 1 3/4 to 2" primaries.
https://ls1tech.com/forums/generatio...-liter-18.html
I'd say stick to 1 7/8's for most all N/A setups.

Exactly what I was thinking, even replacing Kooks with Kooks. Buy new ones for $8-900 sell the old ones for $3-400. People spend more than that all of the time to gain 10-20hp.

 

Your engine thinks like your Girlfriend, the bigger your primary the better