hey i new to the forums but i have the skyactive G mazda 3 and i plan doing quite a few things to my car, exhaust, coil overs, intake, etc. and wanted to know who else has one and we can let each other know how it goes. hmu

 

If you are looking for more noise from the intake and the exhaust then you'll probably be able to satisfy your mod itch, but if you're expecting performance gains from those two mods, I wouldn't bet on any. In fact, given the already high state of tune for the SkyActiv-G engine, I wouldn't be surprised if an intake and exhaust reduced your overall performance.

 

Found this: One thing absent from this production engine is the 4-2-1-exhaust manifold, designed to allow the engine to run at an even higher 13:1 compression ratio. As it turns out, the SkyActiv engine was never intended for the current Mazda3 but was rushed into the product cycle. That header, however, wouldn’t fit and so it had to be left out at the expense of some power and torque. The difference, says Mazda3 engineering chief Kenichiro Saruwatari is more in the low and mid-range torque. It will, however, make an appearance on the upcoming CX-5.
FROM: 2012 Mazda 3 SkyActiv Review: Car Reviews There is also a Video.

ALSO:
With a reasonable amount of power being generated, with 155-hp and 148 lb-ft of torque you wouldn’t expect the car to be lacking and under most circumstances it’s not. Off the line, however, we did find it a bit sluggish. Those power numbers show an impressive jump over the old 2.0-liter MZR 4-cylinder that’s rated at 148-hp and 135 lb-ft. But peak readouts don’t tell the whole story either with the 5 percent horsepower increase and 10 percent torque increase less significant than that 15 percent improvement in low and mid-range torque.

Current Compression Ratio 12:1 due to lack of fitting in that 4-2-1 header.

You won't find any intake or headers for this yet. Maybe Mazda has something, but if it's like their intake for the Mazda6, pass on it as that one used the stock accordian tube (what a joke).

For aftermarket, wait another couple years.

 

yeah that exhaust manifold would of been nice with that increase in low end torque. My skyactiv had was very weak at the low end but it has seemed to have gone away after the initial 1k miles.

 

If, and that is a very big IF, you can find someone to build you a 4-2-1 exhaust header, then yes, it is likely you'll see a minor improvement in power, however, as has been pointed out on this forum any number of times, Mazda tried to do a 4-2-1 exhaust manifold for the new 2012 SkyActiv version of the Mazda3 and couldn't make it fit.

 

Mr Berger - Now that you've had the Mazda 3 for a month, any feedback?