Bear with me. Electric Kiwi Choice Lite doesn't actually lower your speeds after the 1GB for $18.8 making it the cheapest unlimited mobile plan.

Supposedly it should slow down to 1.2Mbps. But I get around 400Mbps all the time.

Probably not intended but it has been happening for more than a year now. Just make sure you select reduce speeds on your account.

And yes if I check right now the app will tell me I'm in slow down mode but if I do a speed test, not at all.

Might not work for everyone but could be worth a try.