I have a 2020 honda civic si and I want to know your opinion on modifications like a blow off valve? I see mixed opinions if it is bad for the car or not.
Running a VTA (Vent to Atmosphere) blow off valve on a recirculating turbo system is not a good idea. The air that you are venting out is supposed to be recycled through the system. The result is your car is going to run rich, you'll lose a bit of power, and your catalytic converters will fail prematurely.
Yeah, I know. Friggin EVERYONE wants the "SWOOOOSH" sound. I have customers ask for that all the time. But I do not install VTA valves on Recirc systems because when the cats fail, I'm not going to be liable for replacing them. They are very expensive.
Bottom line: Don't do it.
If they want that "woosh" sound with the stock turbo bypass valve, then they can install an aftermarket intake that removes the factory intake silencer. And I agree, I wouldn't mess with the bypass valve...no reason to mess with one unless the stock one cannot handle increased boost levels.
Thanks for the help! Yeah this summer I did put a PRL street intake and it does sound really good! I don't plan on doing any more modifications because I want the car to last as long as possible. I do want that swoosh sounds so bad lol but not worth if it is bad. Just was confused because some people online say adding a aftermarket blowoff valve isn't bad for the car and others say it is.
If it was good for the car, Honda would have put it in.
Yes its bad for the car due to messing with the air/fuel ratio. You'll lose about 10-20 whp if you install one in. If anything, just go for an aftermarket CAI. I got PRL race CAI on mine and it sounds just as good. However, the CAI race version does require a tune. If you dont want a tune, just go for the street version.
I got the street because I didn't want to tune and void the warranty... At least until the warenty is up. I love the sound of it for sure!