It's your decision to make, but I will say that hybrids are more susceptible to cat converter theft than petrol or diesel cars. My thoughts would be, if you can afford it then £300 isn't an eye-watering price to pay for peace of mind. However, there are other preventative steps you can take if you're concerned. You can see our advice here: kit.honestjohn.co.uk/top-tens/top-10-ways-to-preve...t

I would research online, too. There's a lot of chat about cat converter theft in forums - and there will certainly be ones that are Lexus-specific. I'd browse some of those to see what other owners are doing.