Just to point out that technically speaking wrapping the downpipe will increase lag. You want everything as hot as possible before turbo and as cool as possible after the turbo to decrease lag.

That being said the benefit of sheilding the TMIC from the heat offsets this added lag effect. Now, if you're setup with a FMIC or on a race car that is always moving I wouldn't suggest wrapping anything past the turbo.

If you wrap any part of your exhaust you need to be sure to use the recommended hi-temp sealant product to seal the installation.