The shop owner also sells/installs Flowmaster - he thought the Dynomax would be quieter on the truck than the Flowmaster. I had a Flowmaster on a 350 suburban and liked it fine - it had a better note than what I hear from the Dynomax, but then that's a different engine and pipe..... after I get the engine tuned, I may try a Magnaflow if there's a size to fit the space..... it's very tight and won't allow a longer muffler.

Matt at DIY AutoTune has advised me to use 6.5A in the calculator for dwell.... that puts it at 3.9msec.... fairly long. I've read that MS does cut back dwell and spark duration at higher rpms in order to fit both within the available time, so I guess I'll set it at 3.9msec and use the old hand thermometer trick at idle to make sure the coil doesn't get too hot.

Dang - all these mathematical calculators and tools and you still need to have some experience and common sense. <img src="/forums/images/graemlins/lol.gif" alt="" />

Frank