While PC manufacturers are revising downwards their notebook shipments for 2011, Apple’s MacBook Air manufacturers are rolling their sleeves up.

Yesterday’s report from the investment research team Goldman Sachs, revised downward its forecast for most of the Taiwanese notebooks manufacturer and shipments this quarter and next quarter. Except for one.

The world’s largest computer maker, Inc from Taiwan, recently told shareholders to expect shipments in the third and fourth quarters, to rise sequentially by 5 and 10 percent and maintained its forecast of a 10 percent rise in laptop shipments to more than 57 million units this year, compared with 52.1 million units for last year.

Goldman Sachs said Quanta remained one of its top picks among notebook ODMs [original design manufacturers], thanks to Apple Inc’s strong laptop demand.

“We continue to see Quanta as the main beneficiary of MacBook Air’s refreshment with volume kickoff in early third quarter,” Goldman Sachs said.

Apple’s refreshed MacBook Air is allegedly due to be released on July 19, and the Cupertino firm is expecting big numbers. They’ve in fact pushed the total production to about 2.8 million units for July. DigiTimes‘ sources suggested that total MacBook Air production for the third quarter of this year might reach as high as 8 million units, or double the amount for the second quarter.