I just installed my dc 4-1 header today on my GS. THe mods i have are AEM short ram, the header, type R cat, type R exhaust.

after installing it, i didnt realy feel any top end gains and felt like i lost some low end. I havnt dynoed it yet but i am quite disappointed with the results.

what could be wrong my friends? should i of went with the 4-2-1 instead?

 

yup....since i know you don't like to search much (from when you first joined han) you should have went with the 4-2-1. A 4-1 header was designed to improve top end for the gsr or type r motor, 4-2-1 is low end to mid range power for the ls or in your case the "gs". PM cause i have a dc 4-2-1 header and wouldn't mind trading you for the 4-1

 

dont expect big gains from a standard production header

 

not big gains but i admit when i did my header and apexi ws on my ls i felt a difference. Wasn't huge but i was deff happy with it. With all mods i've noticed though that after awhile you get used to them and then your car feels "slow" again.

 

The 4-1 header makes more peak power than the 4-2-1, and more power in the upper rpm. If you wanted midrange power, you should have gotten a 4-2-1. You can still make high RPM power on an LS motor, you just need the right combo of parts. You might notice a little loss in the low end due to decreased backpressure, but I didn't really notice any loss. I did notice a small top end gain, but I have a much freer flowing exhaust than you. Like Snoopy said, don't expect to make more than a few hp from a mass produced header, when you aren't making much power to begin with.

 

i did notice that 1st gear pulls harder than it did before. i'm going to do a few more test today.

 

I would have told you to get a type-r header instead with a 2.5 ich collector. Stainless steel with the flange and o-ring, $250!

 

how would a gsr do with a 4-2-1

 

more mid range power, less top end, but just stick with 4-1

 

i have a gsr with 4-2-1 and performs very nice all around