I want to do the following mods:

Headers, Cat-Back, 1.6 rr

In what order do you all think I should do them? and Why?

Thanks

 

Well, if you're doing them all at different times, here's what I would do and why:

1. Cat Back
2. Headers
3. Roller rockers

Why put the cat back on before the headers? The headers are going to greatly increase the velocity of the air moving through the exhaust system, only to meet a bottleneck at the stock cat back system. You should do the cat-back first so that when you do the headers you'll maximize the gains.

Why do the rockers last? Well, if you put roller rockers on, your gains would not be as good because you're only bringing in more air without opening the exhaust up to expel more air.

If you think about, it makes sense. Personally, I'd do the whole exhaust system at once with a high flow cat and be done with it.

 

Thanks fastbird, that seems to make a lot of sense.
Thanks for your input

 

Fastbird,

Going out on a limb here but I have to disagree with you in part. You are correct in stating that the stock exhaust system would create a bottleneck to the effects of the headers, however headers do not increase exhaust velocity, they decrease the exhaust backpressure. They also allow for better flow than the stock manifolds.
In essance the header primaries have a larger cross sectional area than the manifolds. The larger area will have a tendancy to decrease the velocity, however the larger diameter allows the exhaust gases to flow better. The same is true for the catback. Increasing the pipesize of the catback decreases the backpressure, allowing for a better flowing exhaust, not necessarily a faster flowing exhaust.

You are right on the money as far as the order of the mods. just thought I'd clear how the headers effect the exhaust flow.

 

I see exactly what you're saying, but in essence doesn't the reduction of backpressure directly increase the velocity of the air moving through the pipes? Or is it simply a matter of technical terms? I figured they were tied into one another (better flow=more velocity), but I'm by no means an expert. Thanks for the heads up and good explanation.

 

First, my apologies to Storrman, this is going a little off topic.

Maybe this will help (wife however says I'm terrible at explaining things so keep that in mind )

Your correct, flow and velocity are tied together.
An example: You have a balloon hooked to the end of a one of those little coffee stirrer straws. The ballon has been filled to a certain size. Once you let the air go, you will feel the air at the end of the straw and it will take a certain amount of time for the balloon to deflate.
Now take a McDonalds straw, which has a much bigger diameter.
Do the same thing making sure the balloon is inflated to the same size and you will notice that the balloon deflates much quicker (better flow) and the velocity of the air at the end of the straw is lower, since it isn't getting pushed as hard through the smaller straw.

Hope this helps!

 

Gotcha! Good explanation!