what swaps can i do to my 1990 3000gt??

The best stock swap is the 3.0L DOHC 24V Twin Turbo with a 6 speed manual trans 94-99 had 320 HP @6000 RPM the hard part is trying to do it in a stock 2wd. The VR4 was the AWD version so therefore had a different trans setup. Unless your car is in mint condition, or holds sentimental value to you, better off just getting a 96 and up VR4 if that is what you desire.

I agree with Chris. A 1990 car is 22 yrs old by now. It is not worth doing an engine swap, and like Chris said, you will hit some hurdles with the transmission/transfer case as you will need to keep your car FWD. By yhr time you invest several thousand dollars in this swap, you are better selling your current car and buying a 2nd gen (94-99) VR4 with low mileage. I sold my 95 VR4 three months ago for $10K. It was in excellent shape and had 93K miles, always garage kept, with an electronic boost controller and summer and winter tires. Look on the 3SI board, autotrader, cars.com, etc for cars that are for sale. Be willing to travel across the country to purchase a low mileage car. The guy that bought my car flew in from 1000 miles away (two people) to view the car and buy it. If you are prepared to do this, you will find a nice car. Best of luck. -Mike-