I recently changed the exhaust on our 250 from dual 2.25" pipes with glass packs and short exits behind the cab to a homemade 'Y' pipe into a 2.25 I/O 'turbo' muffler that still exits near the rear of the cab. The muffler is a local muffler shop's store brand. The results were more than surprising. The amount of low end power (sub 2000 rpms) is outrageously better. The top end did seem to suffer a bit, but most of the driving is not done over 4000.
For some background, we took on the exhaust changeover due to the old system rusted and broke after 4 Upstate NY salt covered road winters (surprise!), and we were looking something a little less noisy, but still 'throaty'. We did the project at home without the aid of a pipe bender. Also, we are running Langdon headers.
Right after the change I thought it seemed like it ran better, but after driving it for several days I found that I can pull hills that I never used to be able to without shifting down and with much less throttle. It also lost a hesitation that it used to have around 18-1900 when cruising and then applying more throttle. The only thing I assume is that the additional back pressure and/or less scavenging effect of the smaller exhaust is beneficial. And now I can hear the radio when driving and I don't have to shut it off when ordering at the drive through:)
I wish I had put it on a chassis dyno prior to changing the exhaust, so as to have a better, real number comparison. But I never really thought that the duals were hurting the driveability that much.
Haven't posted in a while, but log in occasionally and check things out. FYI - we've put almost 40K on the 250 since the rebuild and it still runs the same as when we first put it together.
