E46 330ci modifications

[Indeedterror]

Hey guys i recently bought a 2003 330ci. Right now im going through the car and doing all the maintenance. It has 170,000 miles and runs strong. After all my maintenance has been checked off im wanting to add some power to the car. Im wanting to turbo the car later down the road. So i guess what im asking is what bolts ons add power and can help later down the road for a turbo?

[XnWarden]

A custom exhaust would drop some weight and it could be designed in such a way to accept a downpipe later once a turbo is added. Do you need to stay emissions compliant?

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