Since I already had my engine out for the loose exhaust manifold repair, I decided to do a couple of mods.  These RC Engineering injectors are 550cc's and 25% bigger that the 440s.  This, along with the Lexus AFM (also 25% bigger) give more fuel and air per cycle with no computer upgrades or other  problems to the Supra.

I purchased the injectors straight from RC, and they even came with a piece of paper showing the flow rates.  I noticed that the RC's spray out of one big hole and the stock ones spray into a "Y" pattern.  The difference in horsepower is supposed to be negligible.  I had to go to 4 junkyards to find the injector connectors off of an RX-7, but now the connectors can be purchased along with the injectors.  I would definitely spend the money for new ones if I had it to do again.  I spliced my new connectors right into the wiring harness as I am very familiar with wiring repairs and a soldering iron.  Some have actually made a a jumper connector to allow removal later.  During installation of the injectors, I put a small amount of Vaseline on the injector seals to make sure that they slid in straight and didn't get kinked or pinched (fuel leaks are a bad thing).

1- The AFM part of this upgrade was very simple, but this part is not.  Since the injector upgrade requires access to the wiring harness, it is a lot more involved.  
2- To me it seemed the best way to get access was to separate the upper and lower halves of the intake manifold.  So be prepared for this extra step. 
3- I had to be extra careful with the spring clips on the new connectors.  The connectors themselves were old and a little brittle. 
4- I did this upgrade as part of a larger repair and already had an upper end gasket set.  I'm not sure if one can get just a manifold gasket or if the old gasket will have to be reused.  It is just paper, so be careful taking the intake manifold halves apart. 

1- I recommend buying new connectors along with the injectors.

This upgrade was expensive, difficult, and time consuming.  However, it is also almost necessary when going for large amounts of horsepower.  I did not included the manifold gasket cost as I already totaled it as part of a larger repair.