1 Lucky Texan

rear diff mount bushings may be worn.

the autos have a wet clutch pack and 'bias' is adjustable by the ECU (or tuning I guess) the FWD fuse just turns-off the duty C solenoid so the clutch pack doesn't transfer any power out the back of the trans. Some folks have modified that circuit for manual switching. The system with it's fuse-selection exists primarily to allow use of the 'donut' spare without introducing torque bind. sti's got an adjustable center diff in their MTs. DCCD I think it was called?

I think there's also a 'pancake adapter' that goes under the oil filter. It creates for a secondary oil pressure port.

what about a JDM ej20 SOHC ? to much engine management issues?

there is a fast twitch eye movement called a saccade that can allow for flicker detection above the typical 120hz of room lighting. something like 1 in 4,000 people may be able to sense flicker as high as 2K . Much depends on the lighting conditions, contrast, etc. http://theconversation.com/the-scientific-reason-you-dont-like-led-bulbs-and-the-simple-way-to-fix-them-81639

the actuators are electric. you might dig around at www.opposedforces.com for some helpful drawings. after google, the world's most popular search engine is Youtube, might get lucky enough to find a helpful video.

another fun idea; a soob diesel EE20 ???

check the timing belt too.

2 liter JDM turbo ? I once saw a Suzuki - uh, Brute I think? 2 cycle engine. For reverse, you kill the engine and start it backwards and use first gear!

true for most people, there still seems to be some studies ongoing for a small number of folks that might 'react' to light flicker. Incandescent filaments have too much mass to cool-off much. Fluorescents might dim to 35% of max. LEDs can dim to under 10% of max so, the effect might be sufficient to cause some subconscious issue with a few people. And if LEDs are used on a circuit with an improper dimmer, there can be other issues. there's a lot of variables though, spectra, type of circuit control used, intensity, mix of natural light, etc.

some people might be sensitive to the 60Hz flickering - much less significant with incandescent bulbs. or you're sensitive to a different output spectra ?????

computer doesn't catch the 14 deleted codes on my WRX (due to frozen air cut valves and related pump)

is the CEL coming back on quickly after a reset? any other codes? You may need to retrieve live data. if it seems worse on a cold morning, you may still need to look for a fuel clamp/connection to tighten. Some folks have had injector seals leak a little. doesn't take much gas to really smell.

11 year old car could have many sources of vibration - wheel balance as said, u-joint seizing, half axle failing, stuck brake caliper, various bushings worn, etc.

stronger out the tailpipe, underhood, in the cabin? - after fueling or ???? sometimes filler tubes can have holes in them under the plastic cover.

you can get 'spark plug spacers' still. at nasioc.com , you might find the resistor values needed to make your own 'bypass' device.

I think it comes down to reliability IF this car we're discussing needs to your daily driver. But, if you have alternate transportation for when the 'project' car is down waiting for repair or upgrade, then that might mean something else. Even a craigslist wrx with a blown motor could work.

so, how much do you guys charge for a 5 to 6 spd swap? I have a local shop that mentioned the same thing, if I'd had 'xtra' money when my 5spd ate 2nd gear, I would have had them put a 6spd in.

seems expensive unless a LOT has been done. individual sale or off a car lot? kinda wonder if someone at nasioc.com might recognize that car.

details on car; mileage, year you're in a good part of the country to take the car to a knowledgeable mechanic for a pre-purchase inspection. HIGHLY recommended - more-so with a used turbo.

you can find a video of someone splitting the case on an STi motor and rebuilding it I think. when a soob engine really dies, most folks get a used engine; junkyard or JDM .

catz - GD is right, most everything under the hood is quite a bit different and of course, different computer running everything. premium fuel needed too. about 90% of hood scoop air goes thru the intercooler, the rest is split and directed to turbo cooling. check www.cars101.com for Subaru specs going back many years.

long ago at nasioc I had read of an alternative plugged port but, not even sure of what engine was being discussed. hopefully, GD ( @GeneralDisorder or some other guru can respond - I suppose there's no reason not to use the sender's port but, there are pancake (or is it waffle?) adapters that can go under the oil filter. sometimes the soobs from the 90s can have leaks on the back of the oil pump from screws loosening. on rare occasions, some soobs in the early 2000s have suffered cracked pick-up tubes. that's about the extent of my help though lol!

tires are stock size?

did she report any clacking/ticking noises too? the OP switch/sender is kinda under the alt. That thing comes on at something like 4psi. If she overfilled though, maybe she still had oil flowing? I suppose we're sure it was the oil light and not - what? ABS or CEL, etc.? anyway, hope the car is OK.