#A4LDPV. A4LD oversize pressure boost valve (1985-1994). When rebuilding high performance or heavy duty A4LD transmissions, it is common to find the boost sleeve in the valve body worn. This wear causes low line pressure, soft upshifts, delayed reverse and poor modulator control, resulting in poor performance or premature failure for your high performance or heavy duty rebuild. These complaints can often be caused by a worn boost sleeve, which allows reverse and/or TV pressure to cross leak or exhaust.