If yours is a VDO ECU, this is what I suggest.

Remain stock filter, replace your snorkel with the flexible pipe for cooler outside air. Those drop ins won't give you any difference.

Get the extractor, after the flexi pipe, use one mid box. Maintain stock piping. At the rear get a big box straight flow muffler (if you want to maintain noise level).

Plugs, use back ori copper plugs, and standard plug cables. Those are the best for stock engine. Don't waste money on those performance plugs and cables.

Lastly, would be regular maintainence. Check fuel filter, clean throttle body, use better engine oil. Regular maintainence will keep the engine healthy. Better than those modded cars, but having blue smoke coming from their exhaust.

I drive a 4g13 VDO myself, and this is so far the best setup after wasting so much money.

Don't listen to those asking you to put 2 inch pipe and so on. Your aim is daily driving, so mod towards what gives your the best drivability for your car and yourself.

Edit: Those lightened crank pulley, will never work on your VDO engine. The crank sensor for VDO and MMC is different, you will feel more power loss than gain. These are the mods that are as close to stock as possible.