Hi,
In the grand scheme of things anything you can realistically do to it won't make much difference because most of the innards are inaccessible.
I did a couple of tiny tweaks to mine while it was last out. I filled in the EGR channels with 2 part body filler (JB Weld would be more suitable though as it will hold fast even when warm). I also sanded down a couple of ridges and bumps, also at the throttle body end.
At the other end I opened some of the ports a tiny bit just to make them match the LIM better. If you put the UIM over the LIM and look down the LIM holes you'll see a slight mismatch. It may be worth improving this a little but you mustn't remove too much material or you could harm airflow.
You could also add a blanking plate for the EGR valve to prevent cack from coming back in.
Simon
In the grand scheme of things anything you can realistically do to it won't make much difference because most of the innards are inaccessible.
I did a couple of tiny tweaks to mine while it was last out. I filled in the EGR channels with 2 part body filler (JB Weld would be more suitable though as it will hold fast even when warm). I also sanded down a couple of ridges and bumps, also at the throttle body end.
At the other end I opened some of the ports a tiny bit just to make them match the LIM better. If you put the UIM over the LIM and look down the LIM holes you'll see a slight mismatch. It may be worth improving this a little but you mustn't remove too much material or you could harm airflow.
You could also add a blanking plate for the EGR valve to prevent cack from coming back in.
Simon