I searched all over for an answer to which of these inserts uses a stiffer polyurethane and couldn't find a definitive answer anywhere.

I finally have the answer after getting a chance to compare these side by side today. The SuperPro large engine mount inserts are decently stiffer than the equivalent yellow Powerflex inserts. The difference could make a difference in vibrations, rattles, etc., but also how much engine movement is allowed too.

Hope that helps if you're trying to decide on which ones to get...

 

I believe powerflex offers a race version of all their inserts as well. Yellow is their street version. Race being stiffer, you can cheap out and buy some 3m window weld and fill in all your factory mounts. Same result and way cheaper, like 20 something for the tube, could do close to 2 cars on one tube as well. I wrote a how to and submitted it but it either got rejected or hasn't been approved I guess. Who do I talk to about that?

 

Yes, there is a powerflex race version. I haven't worked with those at all, but I'm guessing the Superpro ones are a good middle ground between the Powerflex street and race versions.

I've also heard of some people using silicone and baking in the oven to get it to cure. I think that would be softer than the window weld, but I haven't ever done either.

When did you write the how-to? Back when I did one a few years ago, I don't remember how long it took to show up, but it was definitely at least a few days.

 

Been a few weeks. And the oven will breakdown the rubber in the factory mounts. Heat drastically effects chemical compusiotion. Best to let it dry on its own. Silicone would be kinda pointless. To much give and tears real easy I would suspect in a mount. I've got the whole how to saved, I'm thinking I'll just post it in the appropriate section on its own if it never shows up. I need to go take a look lol........