Install/Review: Perrin Downpipe Blanket

I picked this up from a friend, who got it from another friend. So I am the third owner of this blanket so keep that in mind.

I’ve wrapped and rewrapped several downpipes in my life and I’m over it. Although the wrapping process is pretty easy it’s the shedding fiberglass I’m done dealing with. I get fiberglass all over my arms and no length of shower seems long enough. It lingers on the garage floor for weeks. But I digress…

This can be installed on the car, and I initially installed it , albeit hastily, while the downpipe was on the car. This time I pulled the downpipe to inspect gaskets, the turbo, the cat and to remove the final heat shield.

Also this blanket is probably designed for aftermarket USDM downpipes. The JDM DPs have an O2 in the bellmouth from the factory. It doesn’t interfere with the blanket too much but it does keep it from being flush with the edge of the downpipe for 💯% coverage.

First things first, remove the TMIC, turbo heat shield and downpipe bolts. Should be (5) 14mm bolts/nuts on the DP.

Then jack up the car and put it on jack stands. I would disconnect your 02 sensor(s) now.


Remove the two 14mm/12mm spring bolts connecting the downpipe to the mid-pipe. Next remove the 14mm bolt holding the DP to the transmission bracket. If you are stock there may be another 14mm bolt near the upper cat connecting the DP to the transmission. After that, pop the downpipe out of the lower bracket and it should come out.

As you can see, the VF37s come with a bellmouth downpipe from the factory. Why Subaru didn’t do this for the single scroll setup is beyond me.


Next it’s time to remove the heat shield. I could of just cut these welds off but I chose to break them with a prybar and a hammer. I guess I was just in that kind of mood. 


With the heat shield gone, hopefully my rattles are gone as well, and the blanket can now envelope the downpipe completely to provide better heat retention. 


It’s got plenty of room to fit around a 3-inch downpipe if that is your concern. It’s a little loose on my stock downpipe, but nothing to worry about.


My downpipe has a snuggie! 

After reinstallation and a few days of driving I think my rattles are gone. The amount of heat in the engine bay seems to be about the same as before which was to be expected since the blanket more or less covered the same area sans a heat shield.

Overall I would choose this method again over wrapping the downpipe. After a while the wrap on the downpipe becomes brittle (sheds on contact) and at some point will need to be rewrapped again. Especially if you work on your car as much as I do. And I feel like the blanket keeps more heat out of the engine bay then wrap does.

If you are looking to keep as much heat in the exhaust system and out of your hella-functional TMIC, I would recommend going with a blanket. If the Perrin Up-Pipe Blanket would fit my twin up-pipes I would get that too!

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