The negotiations had encountered problems over GM demands that a PSA-owned Opel be barred from competing against its own Chevrolet lineup in markets including China, they said.But the "non-compete" issues were finally resolved as GM agreed to inject "substantially more" into the pensions than the $1 billion to $2 billion it had initially offered, another person said. The sources declined to give further details. Detroit-based GM, which came close to selling Opel to Magna (MG.TO) in 2009, has faced investor pressure to offload its struggling European arm and focus on raising profitability rather than chase the global sales crown currently held by VW.After fending off 2015 merger overtures by Fiat Chrysler with support from her board, GM Chief Executive Mary Barra agreed to target a 20 percent minimum return on invested capital and pay out more cash to shareholders.