what boost gauges fit in the standard pod, size etc, anybody have any pictures
s15 stock boost gauge pod and fitting aftermarket gauge
52mm gauges will fit fine in the stock pillar gauge holder...
or you could do something like this....
http://forum.s15oc.com/showthread.php?2207-How-to-remove-OEM-boost-gauge-and-fit-Defi-gauge-in
or you could do something like this....
http://forum.s15oc.com/showthread.php?2207-How-to-remove-OEM-boost-gauge-and-fit-Defi-gauge-in
I have a 60mm gauge inside my stock boost gauge holder, i just have to trip the inside a bit to fit it, but once its done it looks perfect, from the outside you cant tell anything has been trimmed
+1 on the 60mm. I've got a Defi one fitted, and as Spoonman said, a little bit of a trim with a stanley knife, and it fits like a beaut! 
just seen the replys, cheers ill get one ordered and fitted