On your '01 they may be concerned with the O2 sensors and converters. The engine is designed for the exhaust system so any change to it could cause trouble for the computor. Is very hard for shops to change new equipment with out getting in to legal troubles with the feds. As for your older engine, 2" to 2 1/4" will work just fine. Stepping down to 2" tailpipe will keep the exhaust flowing faster, which will blow the water out faster and keep them from rotting out. The smaller pipe keeps the heat in the exhaust gas, which keeps it flowing faster. Larger more powerfull engines move more air which require more pipe to move it! Joe
