[88Racing]

Okay I know we are kinda blue oval fans here but I doug up a test we did in the mid 90's with two bowtie trucks.

1st subject was a 95 with a 5.7(350) obd1 system tbifi.
Cut out and removed muffler replaced with straight pipe. No loss in power gained .35 mpg. Definatly improved mid range and made towing boat seam easier.

2nd subject was a 96 5.7(350) with obd2 system tbifi.
Same thing was performed and the results to our suprise were this.
Lost 2.45 mpg. Passing became a chore even became more gutless
when pulling. Cooling system ran hotter. Also got numerous o2 cel lights. Put a aftermarket turbo muffler back on and everything was normal.

We figured out that obd2 systems were really sensetive to almost no backpressure situations and maybe that a higher rate of flow wasn't necessarily good for them.

Even some of the motors I built and put into cars, I found that straight exhaust wasn't the best for the motor. I got more power with backpressure and a x pipe.

So look at what you do and make sure it's the best and well tested product for your truck.

Lars