94 civic transmission and fuel injectors question

I am currently rebuilding a 1994 Honda Civic EX with a manual transmission.I have had the block and heads remachined and replace the stock cam with a Gude Performance cam(including the a bullfrog computer). The stock transmision has a grinding problem going into 5th gear.Will i loose a lot of performance by swapping the stock Ex transmission with a stock LX model transmission?

With the engine set up above do any of you think performance fuel injectors will make a major differance in performance?