I have a standard MY01 WRX but have recently changed my standard exhaust for a Magnex 6x4 Oval backbox plus decat centre section.

I wasn't expecting a noticable power gain but I also wasn't expecting the car to feel a bit more sluggish.

Am I being paranoid or is it possible that the change could have had a detrimental rather that positive effect on performance?

I will be having an ecutek remap in 4 weeks or so, which will hopefully make everything sweet but I am confused.....

Thanks.

 

I thought this too when I got a prodrive backbox. Sometimes back-pressure can be a good thing for low down torque so you might have lost a bit of that but gained top-end power.

Decatting has the most significant effect.