What's a good spark plug and coil brand to buy thats not expensive? Something that will perform like the factory parts.

 

You have a Lexus. Plugs only need to be change about every 1000,000. That's probably about 8 years. Don't try and save $20-$30 on plugs. If you're going to do it yourself, go to autozone or similar and buy good plugs. Get some NGK iridium plugs. A set of 6 will cost about $50. Don't go cheap. Go for good. You shouldn't need a coil.

 

Maintenance guide recommends Denso plugs. I believe they are iridium...

 

There's little to no difference in the brand of denzo or ngk. They might even be built by the same factory. There is however a difference between iridium, platinum, and copper. You definitely NEED iridium.

 

Very true: not much difference between the two from my experience, comes down to a personal choice...

 

FYI, Those NGK spark plugs are $7.28 a peice on Amazon right now.

 

I changed spark plugs last night, 55000 miles. I went with Denso factory and they are OK so far.

Getting to the rear ones is a PITA.

 

Were you having problems with your car? There no reason to replace plugs so soon. Factory change is at 120,000 miles. 100,000 is understandable. Half the miles is just a waste of money and time. Unless there was a problem or you like to tinker and then the cost can be written as entertainment or enjoyment. If there weren't any existing problems, you won't notice any improvement.

 

Everything was/is fine, but I'm planning to convert it to LPG and changing spark plugs is recomended.

 

Interesting conversion. I never really considered that. I buy a lot of propane in bulk for work. Generators. But here, propane costs the same as gasoline. So for me, the retro would never pay itself back. Unless lpg can double the mpg. That I don't know. Anyway, good luck with your project.