Hi.

This is not a chevelle question (but I do have a chevelle). If I put headers, flowmasters, new high-flow cat converters, and 2 1/2" pipes on my '98 Suburban 5.7L(350). How much horsepower will I gain, and will I get better gas mileage?

Thanks for the help

Mike

Mike-
One of my friends dads put the Banks system(full exhuast headers through pipes and the cold air induction system as well) on his 94 Burbon with a 454 and picked up 125 horse(it was dynoed before and after) and about 5 extra mpg, although now its not smog legal in CA. I would guess maybe 50 horsies adn a couple extra mpg, the Stock suburbon exhuast is pretty restrictive.

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Steve
64SS-327-4spd-sold to Original owner!
65 Malibu 283/PG!!!
My 65's Homepage (http://www.angelfire.com/ca4/chevelle/)
Team Chevelle Member #71

125 is by far the most gain I have ever heard of or experienced by fixing the exhaust. In most cases you can enjoy 35-40 on a big block.

There is one small problem with modifying anything on that new of a vehicle. The ECM uses OBD II diagnostics to determine if all the required emission equipment is working. If you go reduce the backpressure with the headers and exhaust, you may find the ECM sets a code for the EGR flow too low, or the Catalyst not working. IS this worth it?

What about if I have new catalytic converters. Will that still have a effect of the sensor?????