In this paper, different techniques are used to improve the turbo decoding of regular repeat accumulate (RA) and irregular repeat accumulate (IRA) codes. The adaptive scaling of a-posteriori information produced by Soft-output Viterbi decoder (SOVA) is proposed. The encoded pilots are another scheme that applied for short length RA codes. This work also suggests a simple and a fast method to generate a random interleaver having a free 4 cycle Tanner graph. Progressive edge growth algorithm (PEG) is also studied and simulated to create the Tanner graphs which have a great girth.