About two years ago I bought a 2004 Seagull S6 acoustic at a pawn shop for $100. It's a cedar top and has pretty scars that come with age and use. I should have known better but I didn't realize at the time the amount of top warping/dishing/bellying that this guitar had. I never encountered (or was aware of) this issues with other acoustics I've owned and had no prior knowledge how to deal with it. After a few days of research online it seemed the best approach was try to fix it with humidity over a month or two. I put a damp sponge inside a plastic soap box that I drilled holes in the top and sides. The sponge never made contact with the wood inside the guitar. I covered the sound hole tightly to retain moisture and kept it inside a guitar case. Tried this over a period of almost two months but it didn't have much effect. Went on to plan B which involved installing a JLD Bridge Doctor. I applied tension slowly over a period of a week to help avoid damaging bracing or lifting the top too high. It definitely helped straighten the top, but at the cost of dulling the tone some. At this point I was satisfied with the warp correction but the low E is definitely sharp during intonation tests. I installed a compensation saddle but it had little to no effect. I did all of these correction attempts about two months after buying the guitar. My son has been using it since I did those repairs and now it's back in my possession. It still has the low E sharp issue so today I tightened the bridge doctor a bit more which lifted the strings higher off the neck and I thought would add length from 12th fret to the saddle for the low E to reduce/eliminate the sharp pitch. However, it didn't help. Would decreasing neck relief help add low E string length while also lowering string height?