The spacers do work wonderfully to help keep the intake cooler. Whether it makes a performance difference or not, I cannot answer. I think it did (in terms of helping to "maintain" hp, but it did not make any really).
What I did love about them, is that I found the intake and the head did not match up very well at all (actually pretty crappy). So, with the spacer, I traced the outline of the head on one side and the intake on the other (bolted it up to each one individually). Then with the almighty dremel I made a smooth transition between the two. That by itself probably made some power, but just bolting them on didn't do it without that modification.
You will also find the same thing when putting them on your FS I'm sure. I got on the path of modifying them because I found that they would not fit at first because of the way my head was machined around the ports. So, I had to fix that, and why stop there!
I also noticed that the intake to TB connection in stock form did not line up either. So, I did the same thing there.
For $100, I recommend them and if you put in the extra time like I did, you'll love them.
I did this at the same time as a new ported and polished manifold. I definitely saw a difference, but I attribute it to the manifold not the spacers. Don't be fooled though, it is a bunch of work to get them in there. . .lots of stuff to take off! Plan a whole day (if you're going to do the extra work I described above).
