Fick

I'll be changing my plugs and wires, do the metal sleeves need to be put back on over the plugs or do we leave them off?

grantv

Need, no. Some do, some don't. I put mine back on when I did my headers and tune. Heat shields, good to keep them IMO.

Cybermind

If you're putting on GM or aftermarket OEM replacement wires, then yes. If you've upgraded your wires to thicker high performance or racing wires, then no. These are made to withstand higher temperatures and come with thicker heat resistant boots that do not normally require extra shielding. However, if your car has headers, then you will need the heat shielding in all cases.

xdmikey

When power fab in Houston replaced my clutch they decided to scrap mine.

bigmackloud

I went with the GMPP plug wires and decided to keep the metal shields. I also added the heat insulators over the plug wires for extra insurance since I have long tube headers.

I was amazed at how brittle the old plug wires were. Several of them broke the moment I touched them. So any extra heat insulation you can add is a good thing.

Bill Curlee

They add heat protection to the boot area. Why would you NOT use them??

They DONT detract from HP. They add reliability.

I always use them on my GM Performance Red wires.