Abysmal perfromance of 2005 Vitz RS

[SlowVitzRS]

Hello,

Recently purchased 2005 Vitz RS in manual.
We have multiple 1NZFE powered vehicles in family but they are either Auto or CVT.
Although the car is not for me, but compared to the car it replaces the performance is abysmal.

Before buying I have driven multiple Vitz RS and they all were gutless.
As comparison my 2002 Toyota IST (also 1NZFE powered) does not have this asthmatic feel. I cannot really compare the CVT Vitz RS as the transmission completely masks the engine performance.

BTW the vehicle this Vitz RS meant to replace is a very worn Toyota Trueno 20 valve.

It is a bit disappointing that Toyota stuck "RS" label on such slow car. What is even more disappointing that the fuel economy is not far off the 20v (8L/100km around town).

Unfortunately there is nothing like that here (New Zealand) on the market (Manual small hatch).

What puzzles me is that 2002 IST (1NZFE) has better throttle response (no lag) and revs freely right through to the redline, while the Vitz RS (1NZFE) has very slow throttle response and bogs down after about ~5000rpm.

Before anyone says this is not a sports car, tell that to Toyota with their "RS" badge.

Right now I am planning to do the following:

Check/Replace air filter
Check/Replace spark plugs (the car has done 60000kms, so theoretically spark plugs are still ok)
Clean MAF
reset ECU and go for a spirited drive
Change oil to Motul 0W30 and genuine filter.
Check O2 sensor operation (should not affect WOT operation, but might affect long term fuel trim?)

Anything else I could check?

Disclaimer: yes I admit that almost every car on the road will be slow to me (I drive WRX STI), but I am comparing this car to Toyota IST and Toyota Trueno.