I have JDM type r swap and just got the JDM DC 4-1 header with carsound cat. I have also had my throttle body honed to 64mm. Car is used to autox. I was told by a shop that this could cause a loss of low end, because header has to flow more to produce scavenging effect with exhaust gases. I know I helped top end but will it be that noticeable in low end and in autox situation. BTW Im running USDM DC 4-2-1 with test pipe and apexi WS exhaust. Should I leave that set up or put on my new one?

 

.....why not try it and see? Or better yet, dyno so you can compare graphs.

I haven't heard that one before.

Sounds like an elusive "backpressure"/ old wives tale the shop is telling you.

 

I understand the improvements on top end, I speaking from autox point of view. Sometimes you get in lower rpm range in turns. Or if you screw up a little you drop rpms, just wondering if anyone autox with this exhaust set up? I will definately try it, but will be bummed if I lose alot of bottom end torque. What rpms does the increased flow make noticable difference, when vtec kicks in (5800 on mine) or before?

 

If the RPMS drop too low then downshift.

 

I will have this on by Friday and give my opinions. Next autox is 3-23-02 and I will try it out. Hopefully I keep revs up and love my set up. Just did not want to waste $420 on stuff that could be negative for what I use my car for.

 

Well just had header and cat installed. It screams from 7500 to 8500 rpms. I have to say Im happy . Tuesday I will have my 64mm TB put on. Wed my Konig Greenlights arrive and also a set of Axis Ultimate brake pads for front. Im doing a complete flush of brake fluid and bang, Autox on Sat. So far, so good, Im very happy. It is amazing how a type r motor makes power above 7500 rpm. I cant stop revving it, drove around for an hour tonight ripping the **** out of my car. Not that I street race but I whopped a riced out teg. Dude even had the chrome fire extinguisher and gauges on a pillars. Beat his *** by 2 car lengths. Hopefully Ill be succesful on Autox coarse!