What all do you have to do to a Nissan Skyline to make it legal in the US

1. Switch steering and gas pedals to the left side of the car.
2. Get a catalytic converter that would be street legal and fit the Skyline.

That should be all.

The current Nissan 350z has the same 0-60 time and top speed as the Nissan Skyline GT-R. It is cheaper to get a 350z.

Your Japan Spec car has to meet USA EPA emissions standards cat converters & EGR system then testing & certification. Approx $10,000 then Department of transportation the car has to be made to USA crashworthyness bumber beams side impact door beams & interior flambility standards & headlights auto aiming & cornering have to be changed out there is another 5/10 thousand. Grand Thieft Auto & other games have made a rare car very popular. There were not that many Skyline GTR 4 wheel drive big motor cars made in the first place most left r repaired wreck cars with major hidden problems remember those cars r 16 to 24 years old obslete & hard to find parts for here in USA. ONLY IF YOU FIND A PERFECT LOW km CAR.

Not an easy question to answer the steering wheel issue mentioned above is right in a small way being that each state differs to which mods r needed to make the skyline street legal to where u live the steering wheel being on the left is only needed in a very very very small amount of states.
Other mods again depend on where u live & to which skyline u r talking about IE the R32 models require a bar adding between the rear seats & the fuel tank due to them being close,A common mod to any Skyline in the US is the Emissions need to be setup,other mods would be headlights altered to suit the difference in driving on the opposite side etc etc but as said this is something u would need to find out about at ur local gov transport office & the cop shop,as unless someone on here owns the same model skyline & lives in ur state else no one will know the exact mods to make the car street legal where u live.

Also if the car is not already in the US then u will be looking at getting a R33 spec 2 due to the US gov not wanting any but can not argue with the Motorex crash data for this version of skyline.
All over Skyline may they be R32 R33 R34 which where already ion the country before the set down of rules r classed street legal if they meet mods required & pre decision time.

The Skyline comes as a non turbo single turbo & twin turbo also RWD AWD 4 door & 2 door as well as a station wagon version being the Stagea.
Parts in the US Canada is a good source do to them having the R32 & spec 1 R33 models there,also R32 wise the Nissan s13 shares parts with that,Also Nissan still stock parts back to the R32 which l used for some of mine.
Also there r breakers of skylines all over the World which post Worldwide.
Its true the Skyline has become more popular do the Games etc but the reason the Skyline was on those games is due to them being so popular elsewhere in the World being used by Tuners for years & years & winning racing & changing motor racing rules & even myself loving them since the R32 came out all pre playstation times.
Performance wise depends on which model the actual figures from Japan where false due to the rules on 276bhp only but true GTR figures is around 330bhp stock & Nissan made the Skyline engines tunable hence them being so popular & can tune upto 500 bhp with stock internals & over 1000bhp with more mods the car is popular due to its cost & having a car which is supercar level with tuning & stock handling at that really low cost.

You do not need to swap it to left hand drive, not sure why people keep saying that.

Anyways, closest thing to a R35 skyline in the US is a G35 coupe. l do not recall if they come as an X (all wheel drive) model or not, but the sedans do come as an X model.

Importing an older model is a pain to do, u will have a better chance just buying one that is already here from someone.

Of course if u have the money up front just buy the new (Skyline) GT-R, l think they r stickering for $70,000 right now.

First..DO NOT LISTEN TO THESE IDIOTS THAT KEEP SAYING YOU HAVE TO SWITCH STEERING WHEEL AND GAS PEDALS OVER. That has nothing to do with why they r illegal. Hell.most of our mail jeeps r right side drive. Skylines do not meet Safety & Emission standards for US. This does not mean they r not safe, just that US does not believe recognize the safety devices. The big thing is the emissions. Motorex in California imports Skylines & makes the US road worthy. It takes about 6 months for the inspections & for the US to recognize it meets US specs & its not cheap. Keep in mind that each state also has its own regulations, so if u buy from them, its only street legal in CA unless ur state has the same laws. Here is the link
http://motorex.net/skyline.html#

Nothing, b/c Motorex was the only company that knew how to do it, but they no longer exist. The only skyline you can legalize is the R33, b/c that is the only skyline DOT has data on. With that said, you would make it pass emissions, update it to current safety standards, etc. Check out the link, it should answer all your questions.