Generally, the preferred spot for a sensor is in the manifold, just below the turbo. If you search for "boost gauge" (or similar) you'll get a TON of reading material that will help you. Select "6.5 forum" for better results with the search.
Does your intake have a black, plastic tube that connects into the intake rubber? If so, you really won't hear much whistle with that in there. Remove it and plug the hole.
Last edited by DennisG01; 09-06-2012 at 10:30.
Reason: clarification
1998 K2500 Suburban 6.5L TD 3.73 rear, Ron Schoolcraft 18:1, Kennedy ECM & IC, Timing gears, Splayed main caps, 3.5" Kennedy Exhuast/No Cat, K&N Filter, Boost/Tranny Temp/EGT(Pre Turbo), Ceramic-coated Manifolds, 195 Stat's, 265/75's (VSSB Adjusted) 7,000lbs (on a scale) Remote Mount Oil Filter, Remote Oil Pressure Sensor