this court reviews an argument not properly preserved for plain error). He contends that the acts between him, then eighteen years old, and a thirteen-year-old girl were not violent felonies ■because the girl consented and acts between two such teenagers do not pose a serious potential risk of physical injury. The Government argues that Orozco waived this argument by maintaining his guilty plea when given an opportunity to withdraw it after learning of his armed career criminal status and the resulting sentencing enhancements. We agree with the Government that Orozco waived his argument by maintaining his guilty plea with full knowledge that he was facing a sentence based on his classification as an armed career criminal. See United States v. Cook, 447 F.3d 1127, 1128 (8th Cir.2006) (<HOLDING>); see also United States v. Nguyen, 46 F.3d
holding that a defendant must demonstrate that he would not have pled guilty but for the error holding that a defendant waived the right to contest his sentence based on an enhancement when he pled guilty and explicitly and voluntarily exposted himself to a specific sentence holding that defendant was entitled to withdraw guilty plea upon habeas corpus proceedings where he pled guilty in exchange for an illegal sentence holding that the defendant waived the right to appeal his sentence including the terms and conditions of his supervised release when he agreed to a plea agreement that said he expressly waives his right to appeal the conviction and sentence imposed on any ground emphasis added holding that heightened evidentiary standard of proof is not required where the sentencing enhancement is based entirely on the extent of the conspiracy to which the defendant pled guilty