Quietest Catless Header
 

I'm aware that a catless header is loud so you don't need to tell me that, but are there any catless headers that are a bit quieter than the rest? The only other exhaust component I have is an MXP Comp RS catback and I don't want my ears to bleed whenever I'm just casually driving but want the power that comes with a catless header and a tune. Thanks!!

When I had my HKS for a short time, it wasn't very loud. You might want to get a catted header as the gains won't be much different and it will keep the noise down. Also you're in Cali so... yeah you guys have Nazi noise regulations.

LMAO, we do indeed. The only reason I haven't looked into a catted header very much is because they are like double the price and I don't wanna spend that much more on something that is still illegal.

lol fair point.

The stock one de-catted.

Is the stock decatted really not that loud? Can you give a little insight as to how tolerable it is because I'm thinking of punching mine.

EL will be quieter than UEL.

This.

Why? The stock cat acts as a resonator, so the extra volume helps to reduce sound.
Another part is that the stock header uses steel that is much thicker than aftermarket stainless piping. It's done for warranty/durability reasons but it looks like crap, so no aftermarket company would do that.

The only real drawback to using the stock header is that over time, you'll have more rattle from the heat shields. Keep in mind that sound energy can also cause unwanted secondary noises from other parts of the exhaust system.

It's why the stock exhaust is designed the way it is, it's why there are random pieces of sound deadening material all over the car.

But resonators work with frequencies depending on their size. If "resonator" is short-ish ex-cat "bulb", it's questionable, if frequencies changed/removed by such matter at all. Somehow no aftermarket catback for twins seen had resonators of similar size (with exception being maybe nameless's downpipe optional orb-like helmholtz resonator, but only size looks a bit similar, how such, connected with separate side pipe, function, it may differ).

Most of the power gain comes from the tune. Try getting the tune first and see if you're happy with it

Do you know any dyno plots showing how much can be gained just by tune?

For very rough numbers out of thin air imho expected gains mentioned in Steve99's basic bolt-on guide thread's OP should do.

I have my own best proof; my own dyno tuned car. My car made almost the same power with the tune without the catless headers vs when retuned with catless headers. The difference in runs between each was within 5whp peak. I went with u equal length headers and even in the mid range, there wasn't a significant difference. I'm not saying that there are no gains

Op should get a tune, post average dyno plots. Then get catless headers, get re-tuned, and post average dyno plots. I think they'll be wishing they'd spent the money on tires instead

I installed Borla UE length headers and the results were pretty damn loud even with the stock exhaust.

I'd ordered a Remark muffler delete axleback which arrived soon after, and with that installed too I'm reading 85db inside the car cruising at 70mph. It's almost uncomfortably loud now but I'll enjoy it until I get pulled over.