Actually a cold turbo charger gives you more air flow on the intake. Everyone else is trying to cool their turbos on their diesel and you are trying to heat yours up. I would not wrap the turbo. You will gain nothing except make your engine to hot. Run diesel purge, fix your air filters. Make sure everything else is optimal before you mess with the turbo

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My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory