I have a '99 3500 2wd that finally has 65,000 mi. I have Geno's muffler elim. pipe on. Due to 5th wheel crashing down on bed I was forced to replace it. I noticed the ex. pipe under the bed was rusted out. I could'nt see it from underneath the truck. What replacement system should I go with. Geno sells ANSA and MBRP. I've read good stuff about STAN'S and others. What to do? Thanks guys!