I've got a question on puting straight pipe on our DMAX's, I was talkin with a guy yesterday who owns his own "Performance Diesel" shop here in "Titletown,WI" about straight piping my exhaust. He strongly recommended me not too. He said he would recommend leaving the exhaust stock before using straight pipe! He made the comment about using straight pipe the exhaust is too free flowing and that the engine needs to have some back pressure, and wanted to sell me a system for a mere $695.00. Now the system he wanted to sell me was a 4" with a straight thru muffler. Wouldn't that system flow just as much exhaust as a straight pipe exhaust?So now I'm feeling kindaabout the whole exhaust thing!! He also mentioned that using straight pipe could cause the turbo to cavitate!! Now I'm no diesel mechanic, but I'm no dumdie either. Sooo is any of this true or is this guy blowin smoke up my A$$? I know several of you guys are running straight pipe and I'd appreciate any help/info on this matter. Also some have had ?? on where to find pipe to do this, and what I have found is if you go to a "Big Truck" dealer Kenworth,Peterbilt,Mack, etc...I found the Packer City International dealership very helpful here. they have 3 1/2" stainless flex pipe (which we get 500,000 miles out of on a Big Truck ) for around $14.00 ' and band clamps also. So I can get all needed parts but don't know what to do!!Thanks for any info in advance!!