Resonator delete

I’m thinking of having a resonator delete on my impreza 2.5i(non turbo). It already has a muffler delete. I was wondering how much it would cost about and possible cons that come with it.

Cons… it is noisey to you, your neighbors and the police, especially with no muffler. Get ready for tickets. Big ones if you are in California

You could probably get the resonator cut off and a straight pipe added for a

I meant cons with performance there are no police where I live and my neighbors both have straight piped diesel trucks so I’m not too worried about that lol

There are no cons with performance but there are no gains either. Just noise.

Been there, done that, put the mufflers back on. Had a muffler on my race car, too.

If there are no police where you live I can think of things that are way more exciting for you to do than running a straight pipe exhaust on a 4 cylinder non turbo car! Message me for more info. He he.


Yeah I’ve only gotten pulled over once in my town and it was when I purposely did a first gear pull by the school cop I didn’t get a ticket though lol

Oh, I’ve got stories. Many, many stories. But generally, deleting a resonator (or cat, or muffler) on a late model vehicle won’t yield much power increase.

Yeah that’s what I thought I’m more concerned about a decrease in power it’s already not the fastest car

What’s the reason why you want to do that?
It’s not power, most likely.
Resonator falling off?

No I just want to make it stupid loud lol
While still passing emissions hopefully

It may help, may not, and it could make the performance worse. The engine designers design the exhaust system so that the exhaust gasses from the cylinder that fires prior helps remove the exhaust gasses from the currently fired cylinder. It’s a pretty complicated thing. I expect they use something called “finite element” mathematical modelling. Did you ever take high school chemistry and during an experiment you’d have to make a partial vacuum by running water from a faucet through a T-adapter? You’d take the vacuum from the center tap of the T. Running water at high speed through that T creates a pretty good vacuum. It’s the same idea how the exhaust system works, and the vacuum effect is what helps clear the cylinders of exhaust gasses so there’s room to fill up the cylinder with a fresh air/fuel charge for the next bang. So what you are thinking of doing may not work as well as you think. No harm doing the experiment though and seeing for yourself. You may invent or discover something important in the process, who knows.

I’ve never seen a car lose power by removing a factory exhaust. So I wouldn’t be concerned with that (backpressure) unless you decide to increase the exhaust diameter by a big margin or run open headers. As long as you keep the exhaust pipe diameter the same, and keep the length relatively the same, you can cut off the resonator and muffler and make it sound as gnarly and obnoxious as you want :+1:. I don’t think it’ll be any faster or slower.

George, I could be wrong, but I do not think the automotive designers dive that deep when designing a stock exhaust system. I imagine quite a bit of thought goes into designing the exhaust manifolds and exhaust diameter. I imagine the muffler and resonators are designed to just flow as much as practical while still maintaining a low sound level. Hence my reasoning that you can straight pipe that bad boy with no performance affects (ok, maybe you’ll even gain 1/2 hp at 6k rpm).

You could well be right there SJ. There’s some pretty car-design knowledgeable folks here. Maybe somebody here knows more about what sort of analysis , mathematical, numerical , seat of the pants experience, etc that exhaust systems are designed. I’d be surprised however if some sort of computerized finite element method isn’t used at some point of the design. It’s used routinely to study faucets for example.

I could be wrong. I’m a hack. Far from an automotive designer. But I’ve driven a lot of junky, cat deleted, glass pack installed cheap vehicles :grin:. They always seemed faster when they were loud, not slower. I imagine it’s a placebo affect and the loud stuff has the same power, to be honest. I like quiet now. Unless the exhaust rots off and I’m just too cheap to replace it. :laughing:

AFAIK Mazda is doing some magic with exhaust with their 4-3-1 system, but I think it is more of exception than a norm for stock exhausts

Not familiar, but I’d think the magic happens pre cat? Maybe not, though.

quite simple concept, still has some magic in it:

Appears that the magic is pre cat - maybe in the manifold?

Maybe someone will straight pipe a new Mazda and we’ll know for sure. Hehe. Someone, somewhere probably already has.

Another con is that you won’t be able to resell the car to anyone under the age of 20 without paying to reinstall the parts you removed.

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