new extractors 95 troopy

Hi gang

I have just fitted new pacemaker extractors to my 95 troopy , as we r planing a trip around oz new year and will be towing a caravan .
hoping to get a little bit more power , especially up hill , My question is i have left the old muffler system on ( original ) is this the best way to go or should i , hang the expence and put new 21/2 " system on

thanks bob