Eaton v8

Hi. I have a rear mount turbo that i put together here in australia. Im running a ls 6 liter thats built with oliver rods and je racing pistons that made 591hp on the engine dyno in n/a form. I had a s475 on it with the .9 t4 that created too much back pressure as the rear wheel was not big enough. so i have swapped it out for the s480 96mm t6 1.32 its the 177287 now its alive and a hell of alot of fun. The boost comes in at about 4000 to 4500 at the moment and we rev it to 7500. And realy all hell breaks loose. I will say It does need a tune touch up but the afrs are fine so im not hurting it. Im wanting to know is there anything i can do to this unit to make it come alive at say the 3000 3500 rpm mark as thats where the converter is. I have found no comparison to the t6 1.32 for saying dropping the ar down to t6 1.15 will work eigther or if its worth it for any gain in response. What does a race cover actually do? do you put a lighter wheel in them to spool these units a bit earlier?