I know some people have modded CL7 headers to fit them onto CL9s, but fitment aside, wouldn't the engineering aspect be a bit off? Since the K20 has a 8000rpm, I would think that the CL7 specific headers would be optimized for performance gains with these factored in (and other factors). Whereas, we have a K24 with 7000rpm (stock), wouldn't the CL7 header, not work as well as intended on a K20 and maybe worse than a header for a K24?? Your thoughts?

 

Hondata did a dyno test using the CL7 header on the K24A2. They found loss of power everywhere below 6000rpm, and a 2-3hp gain above. http://hondata.com/tuning_the_tsx.html

 

the header they tested was from toda and tehy said it was the best they'd tested so far... this header looks identical to the design for the cl7 ? Quite a few ppl i know have used headers designed for the cl7 and shown good gains for the cl9.. isnt it the intake manifold that shows the losses? sorry... im a bit confused

 

Also, you're talking about a difference in displacement of 400cc. Outgoing exhaust pulses will be larger than the 2.0L engine's header is designed for. The exhaust scavenging effect that makes a well-designed header give so much of a gain might not be the same.

 

Correct me if I'm wrong but the way I read this they tried and rejected the CL7 intake manifold, not headers. CL7 headers don't fit, they had to use custom designed CL9 headers from Toda.

 

The CL7 Toda headers do not bolt to the US Cat. You need to use the test pipe. When you use the test pipe the fitment is perfect.

The loss of low end torque refers to the RBB CL7 intake manifold - which is very similar to the 06 Civic Si.

It's all in the article...

 

Ahh, yes, my mistake. What I quoted was intake manifold. :p