Im trying to find a good place where to put my Tx, And i wanted to know where to avoid to place it so my connection wont have any intereferance.

I am guessing you are referring to the rx or receiever? If so, try to keep it away from the drive motors or power wires. This will help to avoid interference. Is this a stock HL? Am, FM?</p>

Its a stock, and can i place the rx board next to the speakers without interference?

I would try to keep it away from the speaker if at all possible too.

Also stand the RX on it's side ...Yes on its side it's a old trick that you do in RC cars when you are getting interfearnce or glitching when on it's side you will get less.