So I replaced the original Garrard 401 mat with an EP

I replaced the original mat on my Garrard 301 with the SPEC+ Analog Disc Sheet (AP-UD1)

A nice improvement to the clarity and resolution.

Same... I replaced the original mat of my 301 with a SPEC+ mat and love the improvement.

Thanks for the recommendation. Reading about the Spec+ gave me an idea.
I just swapped the 10" vinyl record (Daughter - His Young Heart EP) for a 10" shellac 78.
Wow! All the improvements listed above even more pronounced:
1. Lower surface noise
2. Improved depth
3. Hearing further into recording
4. Better focus and more neutral.

noromance,

I played around with several mats and found the original Garrard mat on my 301 sounded best. Same with my Dual 1229. I do like the original Oracle Platter mat and will use it occasionally.  A audio buddy of mine recently bought a solid copper mat and I was really impressed by it.

I also like your idea of using a 10Ep. I have some 78's and might give that a try as they are very rigid and flat.  It seems that the softer the mat the warmer the sound. The harder the more dynamic. 

N.

@normansizemore 
Yeah, I thought the general consensus was leave the original mat. But I have to admit the improvement is not small. I've swapped between the original, the 10" vinyl and the 78 using a number of tracks. Considering I've a stash of old shellac 78s, I think I'll repackage them as a miracle mat for $300!!