Impreza GX MY01 upgrade advice

[swooper]

I'd appreciate any decent advice on the things worth upgrading on a my Impreza GX MY01. Its a 2 litre and pretty immaculate at 138 800. It's my first subaru and im considering what are worth while investments for the sake of performance, and anything else.
Thus far, i have read that a larger exhaust manifold is the easiest bolt-on performance upgrade? Any hints there? Other suggestions?
Looking to create more of a sleeper as they call it... not loud, not crazy, just some sensible rims, good quality sound system, and some nice power when needed.
Many thanks

[Rabbitoh]

I'd appreciate any decent advice on the things worth upgrading on a my Impreza GX MY01. Its a 2 litre and pretty immaculate at 138 800. It's my first subaru and im considering what are worth while investments for the sake of performance, and anything else.
Thus far, i have read that a larger exhaust manifold is the easiest bolt-on performance upgrade? Any hints there? Other suggestions?
Looking to create more of a sleeper as they call it... not loud, not crazy, just some sensible rims, good quality sound system, and some nice power when needed.
Many thanks

For the amount of money you might spend maybe upgrade to a 2.5 RS Impreza.

[Bumpty]

* NA subaru engines aren't meant to be modded for performance. $$ for no (not much) gain..