There are few things that you can try and check... First thing I would check for is exhaust leak. You might not hear them but there can still be some leaks. Check if you have big holes in your fire wall that need to be covered up. Where is your wastegate routed too? if its dumping out to atmosphere it might be throwing a lot of fumes (in boost when the wastegate opens) in the engine bay and getting through your car. You might want to route it back into the downpipe. I would never do it lol, but its the best way to get the exhaust fumes away from the front of the car.
I had that problem in one of my 240's that had a 1jz in it. I had a tial 44m dumping straight down, and my car was really rich when i got into boost and the wastegate opened it was pretty bad.
Also make sure you don't have any fuel leaks any were to, just in case.
