I am to belive if you wrap the headers and uppipe and downpipe etc that the gasses will flow better from the car and contain the heat from the engine bay,

Will you gain a few hp from doing this ? or is it to protect the engine as well ?

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heat wrapping speeds gas flow, reduces underbonnet temps, it's supposed to liberate a few horses although don't expect anything you'll be able to feel through the seat of your pants, but every little helps, IMHO if your fitting a new exhaust or have to remove the old one for some reason then wrap it, but I wouldn't bother removing it just to wrap it.
Most people wrap the manifold (headers), up pipe and down pipe/ de-cat pipe (front section of exhaust system), I have seen the complete system wrapped but I can't see much point in wrapping anything other than the front section, those are the pros , cons, some say it can increase the risk of cracking due to hot spots near joints, it can be a pain to fit unless your removing the system, also if you use a cheap wrap it can drop to bits and cause a right mess, so use decent stuff like DEI or Cool-it etc, the wrap will also soak uo fluids water, oil etc so spray with a high temp sealer.

 

Stops your car melting near the headers too

TX.

 

thankyou for your help