how do you know if your car is running lean my dad just added a couple of things like intake,plenum,tb spacer,tp,and y pipe and know he scared of running lean anyway to tell ??

 

I can tell you right now you are running lean. Plenum spacer alone will lean out the motor some. Test pipes will really make it lean out. But your motor isnt running lean to the point its really hurting the motor. I had the same mods but had high flow cats instead of test pipes and my motor ran lean. Easy way to tell is pull out your plugs and look at them. My platinum plugs were white and the electrodes were almost gone (100 shot of nitrous), but the car ran and idled fine.

Here is a dyno chart showing my lean car vs my car with a tune: