Well if it's coming into the cabin excessively then you could have an exhaust leak on the test pipe. Did you replace the gasket on the header/test pipe? Make sure there's no leaks on the 'Y' pipe connection either.

But as eveyone else says....that is what happens when you get open piping. Get some high flow cats if she doesn't like smell.

 

Yes yes I know it is hard to believe but trust me on this. If you remove the component that burns fuel that the engine does not, then the exhaust will smell like fuel. Crazy isn't it!