I have had a Alvarez classical guitar for around a year now and love it, but I have high tension D'addario strings on it and have had them for about 5 months( im getting new ones soon). My friend told me today that high tensions will warp the neck, is he right? I always worry about things like that since I cant afford to get a new guitar, so do I have to worry about the high tensions warping it?
No. High tension strings are fine. They will not cause any problems to your guitar.