I install test pipe on my car before 2 months , I get 288 whp on dyno jet .
After that I bought ARK exhaust and I get the same horse power 288 whp but my car was too rich 11.5 on high rpm .
finally, I install stillen Gen 3 , I get 305 whp but the car too lean in low rpm 14.7 and 13.6 in high rpm . What is the wrong ? should I remove the intake or tune ? What is the best chip ?

please help me , my car G37 sedan 7A-T 2010

 

It's normal, the intake pipe diameter changed and the airflow into your engine slightly increased. You will need a tune to adjust your AF ratio. Get in touch with an UpRev locally. Are you in the Middle East?

 

Yes, Iam from Saudi Arabia
Is there a dealer in Jeddah city ?
Is there a problem if I use car lean ?

 

Yes you can fubar your motor if you run it to lean. Check here..

UpRev - Engine Management

 

So the ECM is incapable of correcting for higher intake and exhaust flows?...thus requiring a tune?

 

That is corect. I think it will only do so much without a tune.

 

Interesting, thanks for the reply.

 

Oh Jeddah, that's gonna be quite a drive!

But if you do, there's are a few places experienced with tuning our engines using UpRev

 

Isn't 14.7 at low rpm actually still ok. It is where you get into the higher rpms that you need start worrying right? That is what I got out of the A/F ratio deal when I was tuning my Supra Turbo