hey dont know any in phenoix but try hotroddiesel. ca, hes got custom 5 inch stack kits, (competition stacks) there 4 inch off the turbo and step up to 5 inch after the downpipe , through the box with a 5 inch splitter and then up in side the box, (this is maximum flow) they flow great and sound even better, he custom orders and makes a great product ive had mine for 4 years never a problem . hes reasonably priced for the hassel it takes to build em. good luck