High flow cats and front halfed exhaust

[GeneralMotorsguy]

I have a 97 extended can short box Z71 with 5.7

 

Ive put a custom cold air intake and thbdy spacer form airraid,

Ive also rear halfed my exhaust putting on new larger diameter piping from cat to a dynomax ultraflow into single 2.3/4 inch single pipe

the truck had tonns of power as it is

and had nice sound as it now.

I have a hypertech III comming in the mail soon

but I was wonderin if front halfing my exhaust with larger y pipe from stock easily accessible manifolds

to Dynomax SuperConverters.

My exhaust guy says itll make it retardedly loud but itll stand on its tail and really go like stink. Does he just want my 600 bux

altho i do get mad deals.

Retail price for what hed be doing is 800plus.

Id appreaciate your opinions and advice.