TunedRX300

On one hand, I am with Lil4x that one needs to adjust his/her expectation. For example, 220 HP is the maximum at the crank for one particular RPM. One can not drive around with one RPM, just take a look at the technometer, it is unrealistic to expect max HP at 1000 RPM when the peak is reached around 5200 RPM.
On the other hand, if 1mz-fe is sufficient for Camry, it is not enough for the heavier RX. Fact is that is Toyota's design, and we willingly paid $. Not satisfied? Do some mods!

anulex

It’s basically the same engine in the Camry but it’s not totally the same. It s different in many ways. For one, the engine management is TOTALLY different hence y then can and extra 20 hp and 8 foot-pounds of torque out of the RX 300 hp (200 horsepower and 214foot-pounds of torque in the Camry vs 220 horsepower and 222 foot-pounds of torque in the RX300). And, the layout of the total engine package is sort of different. Hence one of the reasons y u cant put a supercharger for the Camry on the RX300. With that said, people always talk about things are under-powered. Japanese vehicles are not torque monsters. Most time you have to rev the crap out of them. You have press that right pedal. I am totally satisfied with my RX Power. I am very dissatisfied with artificial limiter of 112mph. Now that I can do without. I have more than adequate tires.

cary1

Depends on the vehicle. You ought to try my 4.5L straight six Landcruiser. 212HP and 275ft/lb of torque. Throw the TRD blower on there and you are looking at 300hp and 400 ft/lb torque.

TunedRX300

I think the main difference is from intake and exhaust, not the engine itself. It is the same 1mzfe engine core (compression, displacement, etc). Take a look at 2gr-fe, it is used by GS350 and IS350, slight difference in torque/hp because both intake and exhaust are slightly different. But for NA engine, it is very hard to squeeze 20% more power out. You needs SC or Turbo to get to 300hp.
You are right, 112 is limited because OEM tires are S rated, not that the engine/tranny/driveline can't handle >112mph.

HarrierAWD

My 2002 RX300's engine bay layout is identical to my neighbor's 1999 Camry V6.

I do not know why TRD didn't bother to make a supercharger for the RX300. Maybe it's because of the dual intake design of the RX300 (hence the increased HP and torque compared to Camry's.) Ironically TRD does make a supercharger for the Sienna minivan.