Hey guys.

First off, I'm maybe considering a muffler for my Cobalt. The thing is though, it's auto. I hate when guys slap loud ass canister mufflers onto auto 4 cylinders because it usually sounds rediculous. A guy at my school has one on a Sentra and it makes babies cry. Regardless, I'd like the power, without the sound. I know there has to be a few mufflers out there offering that.

I noticed that Apex-I makes their famous World Sport in a universal muffler now. Would that be a good choice? The WS's were supposed to be barely more than stock I always thought. A link is below.

World Sport: http://www.cobaltperformanceparts.co...8357aff9fd187b

Other Options: http://www.cobaltperformanceparts.co...8357aff9fd187b

Thanks!!



Also, injectors. I'm not new to cars, but have never looked into this before. What does upgrading these do? Milegge? Performance? Reliability? I have no idea. what is too much for street use? My car absolutely MUST be daily driver-able. It can't be stallin' out at redlights. Are the factory s/c ones a good upgrade? I have absolutely no idea. What do the s/c ones rate at?

Thanks!!

 

The GM Touring Catback would probably sound pretty good and mild enough to not be ricey. The Sport is louder, but deep and not rice either.

Upgrading injectors will allow you to add more fuel for more power via more air in the cylinders or more RPMs.

 

Word. So what do the stock 2.4 ones rate at? How about the stock s/c? What is a good set to get? I saw all sorts of numbers...

 

The stock LSJ injectors are 34 lb/hr. Stage 1&2 are 42.5 lb/hr. I'm not sure what the LE5 injectors are. Every 14.7 psi of boost roughly doubles the displacement of a motor and Stage 2 is rated for 14 psi according to GM and Stock is ~12 psi so either one should be an upgrade for you.

 

I'm not sure about the size fuel injectors you have stock but if you are stock, there is no need to upgrade your fuel injectors. Like he just said, when you start changing the amount of air a great extent, then changing your injectors would be a good idea. The major reason for changing your injectors is to keep them from overworking.

Just like anything car wise, everything has its limitations. Your injectors are constantly opening and closing causing kenetic energy...too much kenetic energy can cause them to fail. How do you know how they are running? Well, it's called the duty cycle. Rule of thumb is to try and keep your injectors from running pass 80% duty cycle.

Another thing, when changing your fuel injectors...you need to have a way of controlling how much they spray during idle and low throttle driving. When you put bigger injectors on, they are of course able to spray more fuel. If your computer is used to running a % on your stock injectors and then you put bigger injectors in, that % will have your injectors spray more fuel which will cause rich conditions and quite possible flooding of the engine depending on how bad the situation is. The only ways of keeping this from happening is by using something like HP Tuners to control the duty cycle (alter the duty cycle) OR by adjusting your fuel pressure.

To break it down...there is no need to upgrade fuel injectors unless:

1. You're over exhausting the injectors (example: running pass 80% duty cycle)
2. You have a way of controlling how much fuel is being sprayed during all driving conditions.

Hope this helped.

 

It did.

 

As far as the 4 cylinder cars that awful according to you, there is much more to the sound of a vehicle than it's muffler. I've seen cars with very deep exhaust tones (4 cylinders) and canister mufflers.

Read this: http://www.ecotecforum.com/forums/showthread.php?t=1999

^^ That will explain why an exhaust system sounds the way it does.

A muffler change doesn't typically yield much gains if any depending on the vehicle and how much restriction that stock muffler is creating. If you're going for performance, I would look into upgrading your whole exhaust system, not just the muffler.

 

Glad it did. If you have anymore questions, feel free to ask me or post it up.

 

Will do! Thanks!

 

No problem