Exhaust System Backpressure

93Stocker · March 8, 2004

I'm looking for a replacement for the OE exhaust on a '93 K1500 pickup, 141.5" WB, 5.7L engine. The current configuration is 3in. from the cat to the muffler inlet and twin 2.25in. tailpipes in tandem out behind the rear wheel. I want to replace the twin tailpipes with one larger diameter pipe, probably 3in. I plan to use a stock type (sounding) muffler. The muffler shops I've talked to say they can do this using a universal fit muffler and bending the tailpipe themselves. No one has been able to tell me the difference in backpressure between a universal fit and direct fit (OE style?) muffler. These shops use either Goerlich's or IMCO mufflers. Any advice on whether or not the backpressure difference is a concern would be appreciated.

LikeaRock14 · March 8, 2004

Lol, well, there's tons of universal mufflers out there. For example, all of Magnaflow and Borla's straight thru mufflers are universal, AND they're universal. I'm not too good with o.e replacements, but a Basic turbo muffler should do the job. Of course with the Magnaflow type iniversal you'll have less backpressure, losing a slight decrease in low end, but it's not li,ke it'll be horrible.

As with a turbo style stock replacement muffler, it should have more backprssure, and with a high-backpressure muffler going to like a 3" single out shouldn't make you lose any backpressure. Every aftermarket muffler has even a little bit less backpressure than stock, and it will probably be a little deeper.

I'd say just throw a flowmaster 50 series or 70 series underneath, it'll sound nice! More power, and it shouldn't be annoying!

My $.02!

Dolan

93Stocker · March 9, 2004

Dolan,

Thanks for your reply! I've looked at performance exhaust websites for Flowmaster, Magnaflow, Dynomax, Gibson, etc. I decided to stay with a stock type muffler. I'd like a deep, throaty sound but quiet inside is more important to me. Getting ready for a long highway trip, don't want the drone of a too loud exhaust.

One reason I asked about the backpressure is because of what I read on Goerlich's website. They say their MSL muffler is designed to meet or exceed OE specs for backpressure. I don't want to lose power or decrease gas mileage. Appreciate your $0.02!