I'll put in my thoughts here..........as its my car

In std form there was little lag. Adding the stage3 head and PE cam lost some of the bottom end response but it was still pretty good and the softer torque curve made sure that it stopped eating gearbox bearings.
Adding the Stage2 TT blower made it sooooooooo much more laggy. You'd really have to think ahead to avoid the lag. Catch it in the wrong gear and a Fiesta 1.1 would be sailing past.

The spec of the Stage3 isnt so different from the Stage2 but I think the important thing here is that Linsay is running less boost with a much larger intercooler so she can run more advance which will give it better response.

Either way its hard to get round the fact that the larger the housing the more laggy it will be - thats basic fluid dynamics. The same zorst gases are coming from the engine but now they have to spin up larger heavier blades in a larger zorst chamber so the force is reduced - hence more lag.

I havent driven it since the addition of the stage3 blower but (and no disrespect to Linsay) she said it wasnt so bad with the Stage2 which to me tells me that she loves the car so much she jsut see's past its shortcomings.

My advice is to go for an intermediate turbo that wont be so laggy. My favourite set up of any RST I'd driven was with the std turbo running 1bar boost and with a good head and cam. Nice wide power band with little lag. None of this all or nothing delivery that feels fast in a straight line but on twisty narrow lanes you never get the reponse to make decent progress.