CanyonCarver

I put a K&N air filter and SuperTrapp mufflers on my Z. My kid said "eewww, you don't put SuperTrapps on a Z". I said "yes I do". I've been using both of these items on various vehicles since 1979. Another reason for going with Supertrapp mufflers is because they don't look like all of the other chrome tipped coffee cans out there. People really take a 2nd look when they see these things with no hole in the end.

At this time I put the mufflers on with new pipe from the resonators back. I'll do a full exhaust after one of my CA smog checks when the guy tells me I need new cats. The mufflers had a LOUD resonance in the 2500 rpm range, almost loud enough to rattle your fillings. Surprisingly, the K&N eliminated most of this. I got two new mufflers off ebay for $110 total including shipping.

K&N filters speak for themselves. If you've ever been thru the silt beds in mexico, no filter works better. I got my K&N off ebay for $15 total including shipping. This was before everybody wanted a cone filter. I made my own adapter.

And the results....... Before I put the mufflers on I got gas mileage of 22.8 to 23.1 mpg. After I put the mufflers on I got the same mileage but the butt dyno said better acceleration over 3500 rpm. The real improvement came with the K&N air filter. I now get 23.7 to 23.9 mpg. The butt dyno says even better acceleration from 3000 rpm on up.

The mpg improvement equates to an increase of 3.4%. I will recover the cost of these parts, in fuel savings, in 24 months. Can any of you mathematicians come up with what the horsepower improvement would be?

91zxtt

You mean that your butt dyno doesn't do thhose calculations for you???

Mufflers and a hi-flow intake on an N/A will give you minimal gains. I'm assuming you installed the drop in K&N filters instead of the cone intake, you'd be lucky to see 10HP more. A cone filter won't give you much more than that. Maybe another 5HP, if your lucky.