This link may help as it contains decent photographs of both engine of that TAG Porsche era along with very clear pictures of turbo external detail including id plating.
Turbo information Mclaren MP4-4. Quoting extracts pertaining only to the turbocharger form an otherwise very exciting to read full technical information of the 1987 TAG-PO1 1.5-LTRE PORSCHE V6. ''TAG PORSCHE TTF-PO1'' - Long time Porsche partner KKK supplied the engine's twin turbochargers, frustratingly for perfectionist engineer John Bernard, KKK took a year and a half to produced mirror-image units that allowed him to improve exhaust-gas flow to right hand turbocharger. Porsche's own wastegates, finned for cooling, provided boost pressure control in the exhaust manifold just upstream of the turbine. The turbine-compressor delivered through air-cooled intercoolers to individual plenum chambers feeding each cylinder bank. Three different turbines and two compressor types were available for the HHB MODEL KKK turbocharger, these could be mixed and matched to tailor set-up to the circuit. With the larger turbine giving more power but at a sacrifice in throttle response. Typically power in racing trim was 820 bhp @ 12000 rpm with a boost of 36 psi. With higher qualifying boost of 41 psi horsepower exceeded the 900 mark.
