The exhaust on my 110 has just about given up and I am looking to replace it. Exhaust shop thought I would be best to go for 2 inch pipe and fit my twin outlet headers. I currently have headers that have a single outlet but my parts car has the twin outlet version, must be manual/auto thing. I am sticking with the single carb for now so what are your thoughts on pipe diameter and manifolds to get good performance and nice note without the dreaded drone.

I would say look into a resonator. They sell relatively cheap resonators you can put in line to cancel out the drone and help reduce overall sound.

Also is your car stock? If so 2" pipe may be overkill

Yeah sorry, forgot to add that info on the engine. L24 is stock and the single pipe fitted at the moment looks to be 1 3/4 inch.