i have a s4 TII. only engine mods are HKS cone filter, 3" exhaust and FCD. not 100% sure if FCD is working properly. heres my dilema:

it pulls fine when i'm just going in a straight line. but if i am cornering hard or drifting the car tends to bog struggle right around 6k rpm.

 

Is it possible this is only happening when you're low on gas? If the car is being steered while you have a low tank of gas, perhaps the fuel pump is not able to get fuel? I'm just taking a shot in the dark, though.

 

sounds like a clogged fuel sock problem,or Sloshing in the tank(due to low fuel in the tank)..Does it do it when you have like Say a Half tank of Gas in it?

 

yeah. it does it when i have a lot of gas.

 

i had the problem too before my motor blew, it woul dhappen when it boosted over 10 pounds, ifound out cuz its not enough fuel entering the engine, too lean, upgrade the injectors and fuel pump..