Fast spooling turbos

Hi guys, am new to this forum so please excuse me if this has been discussed before and point me in the right direction.

I have a series 7 RX7 running a twin turbo setup. At the moment i have the vehicle running these to both come on boost at 4000rpm rather than the sequential setup from factory. As such i get the effect of a single turbo but with almost no lag and when i drive the vehicle nicely i get decent mpg. My problem is that these are small turbos, which will have to work very hard with high boost to get the reliable 400rwhp with these same characteristics, eg no lag, which i want.

From what i have read and discussed with others a single turbo will always have a bit of lag. I was wondering if there is a single turbo out there which will fullfill my needs or two smaller turbos which i can run and get more power from than my stock factory ones?

Any help would be much appreciated

Two smaller turbos have a slight inertia advantage, meaning they can spin up slightly quicker than a single of similar flow capacity.

Otherwise it's much of a muchness. Your rotary produces more excess exhaust heat than almost any other engine so spooling turbos isn't much of a problem.

If you are racing you will only need the top 2 or 3 thousand of your revs so why not go with a single turbo and save gas when driving and make lots of boost while racing?