Questions about headers.
 

Sorry if these have been answered somewhere among the mass of threads but hopefully I can get an answer without too much search flame.

- So can an aftermarket header effectively eliminate the torque dip completely (on petrol)? I've seen many dynos from different manufacturers but some dynos still have the dip and others use e85 so it's difficult to tell. What kind of gains can one expect by adding headers to a catback with tune? Against most dynos are have other mods already on or from bone stock and such.

- How difficult is it to install headers yourself? I believe I read it wasn't too difficult but will I need to take off my existing exhaust to put on the headers and put the exhaust back on after? Will I be able to add headers if I already have another brands aftermarket exhaust? (I have Tsudo which replaces the cat with a highflow cat).

- UEL vs EL? Are the gains the same? Does the sound change significantly when adding onto an already aftermarket exhaust? I've read from other suby one sounds more rumbly or one sounds terrible. I haven't been able to find anyone with headers to listen to the sound yet so just wondering.

- Can I get a catless header and still pass emissions?

Most headers seem to be in development still but definitely my next mod if I can eliminate the torque dip even if gains are meh. Thanks in advance for clearing up my confusion.

1 - Have a good read here.

2 - It's do-able yourself. You don't need to remove the whole exhaust, just the front components (OP/FP) to make it easier. The fitment is designed to be a direct replacement of the OEM manifold so yes, any exhaust system is fine.

3 - Gains for UEL / EL are likely to be similar, it's down to boxer rumble (UEL) or not.

4 - No idea, I have no idea what USA emission laws are ;)

A catless header is illegal in USA, but you can add a spacer type thing 'defowler' to trick the car into thinking it still has one. This is why I'd very much like to see more with high flow cats instead of catless. Seems like 99% of them are catless. Just because we want a better header doesn't mean we want to hurt the environment more or run illegally. (That's a note to header manufacturers)

By the sound of it adding an aftermarket header will make the car much louder. Is the difference as pronounced as going from stock catback -> aftermarket?

Headers seems to be the mod that makes the car much louder than any exhaust system. When you add a header to an aftermarket cat, or header-back system, even more so.

For an example, where I autocross, we have a strict noise limit of 96db from 60' at Wide Open Throttle (WOT). A guy places a sound pressure meter at a section of the course where everybody "should" be at full throttle and records the levels of people as they go by.

I have one of the loudest aftermarket cat-backs available which is the Buddy Club Spec II which is a single pipe with a small resonator just after the cat. I only blew 90db.

There was another guy there (he's a member here but I can't remember his username) that was running a full header, overpipe, catless front pipe and cat-back. I believe it was the Agency Power system but don't hold me to it. Even though his cat back would have been MUCH quieter than mine, he still blew around 96.8db at WOT. While it sounded AWESOME, it was definitely much louder than me.

Scott

Adding a header (FA20club's header, specifically) onto a STOCK cat-back won't be that loud. It's like going from stock catback -> quiet aftermarket catback.

I have headers, a 2.5" over & front pipe (catless, but resonated) with my stock catback.. I haven't measured the Decibel levels, but trust me, I hate loud exhausts, and it's not that loud.

I'll probably have to wait and hear it for myself I suppose. Worst case scenario I want to avoid is spending a grand on headers only to hate daily driving.

The YouTube video of the blue frs running an agency power exhaust sounds angry.. I would love to know his exhaust set up and how loud it actually is

Sent from my Nexus 4 using Tapatalk 2

One other question:
4-2-1 or 4-1 header. Who does what? Is Nameless 4-2-1

Defouler plugs don't work.

if you maintain the cat in the midpipe you'll pass a sniffer style emissions test.

if you tune out the CEL and leave the midpipe cat you SHOULD pass any testing.

With one cat your car will not hurt the environment anymore than with both. (the header cat is there just for start-up )

I don't live in a Communist state and therefor don't have testing. *Grain of Salt

Question about tune for CEL when installing aftermarket headers: What tune would it be to kill the CEL? ECUTek?