I read about import builders modifying JG headers to have a 2.5" collecter. My question is, i have DC Sports 4-1 can i have that one modified as well? or is it something to do with JG and it's a secret? tia.

 

no you can modify your DC, but the JG is much higher quality header, doesn't hang as low as the DC and the piping is bigger with a clean finish. I wish I had a pix of my JG header to show you.

 

i have seen pics. my firend got his done, wil i benifit from it? hacking up my dc SS is not what i really want to do.

 

the 2.5 collector will help pull the top end much more smoother. Notice all the $1000 headers (toda, jun, all the 'good ones') are a 421 w/ a 2.5 collector. the 421 design helps midrange torque and the 2.5 helps all the power carry out over to the higher rpms. I dont see why people will spend $500 on a modified JG, when they can just get a type one for $525 or 600 or whatever they hell they are.

to answer your question, if you put a 2.5 collector on your existng 4-1, you will see better gains in the higher rpm band, and you may lose a little low end. ( personally, when i switched from a 4-1, to a jdm 4-1 i didn't notice squat on the low end, but definately pulled on the high end )

you can find a reputible muffler shop to do this mod if you are serious about it.

 

I'm still debating on if i trade a 421 for my 41 for this mod. My friend owns the shop so it would be basically free, or if i should try and do m 4-1...or just leave it all alone. I don't drag anymore, it's just to do the "little" things to get better performance, did i mention it's free.

 

Don't waste your money switching back and forth between headers. It's not gonna make or break your setup. Focus on building up your engine with more improtant things.

 

that makes sence, but it's free. so is it even worth being free? I'm not gonna build some track monster anyway. i have a few other cars for that. i just wanted to know if it's free, will it be worth our time to attempt it, or should i just out a high flow cat or straight pipe?

 

Why do you feel you need a 2.5" collector?

Do you have a 2.5" exhaust system right now? Do you plan on making over 200whp NA?

Not necissarily, it is possible to lose power on the high end as well as the low for several reasons. First, if your engine does not produce enough exhaust to warrent the use of a 2.5" collector and exhaust system, its going to cause exhaust velocity to slow down. Second, if you go mismatching your exhaust system its going to cause turbulence, and again slow exhaust velocity down.

If at some point you plan on making more than 200whp NA, or go N20/SC (which will require more than bolt ons), then a 2.5" exhaust system will be what you want as part of your engine package.

Most of the 4-2-1 headers you speak of are more or less, "hybrid" headers. They have very long primaries, and are more or less a combination in theory of 4-1 and 4-2-1 headers. So cutting up a comptech 4-2-1 is not going to provide the same results as a Hytech, SMSP, Spoon, etc.

The location of the primaries, secondaries, and collectors all together effect where the powerband is in the RPM range. They don't use the 4-2-1 design to keep midrange torque up until you get to the high RPMs where the collector kicks in, they all are designed for a specific powerband. Having the 2.5" collector, its designed towards engine packages that are much more than just boltons.

 

thanks for all the info. well my goal is only 200 or less whp...well not that i care about that either, but just to do it i guess (header mod) but i'll keep what i have and get a 2.25" cat or test pipe. i have an itr exhaust btw. thanks for all the info.