the turbos aren't sequential (ie not primary and secondary), there are two turbos working in parallel - one turbo per bank of three cylinders given it's a V6 engine. The turbos are quite small, they are twin TD025 which is about 2/3rds the size of a TD04 on a 1.8L Lancer GSR Turbo. They should spool up just about instaneous from approx 2000rpm but will run out of puff towards 6000-6500rpm.