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1 month update:

As some may remember, when I had this exhaust installed, some modifications were needed. Mainly, the extension of the tips and about an 8" extension to the mid-pipe.

When I first drove the car, it was quieter than stock. Of course, the first thing that came to mind was, "$hit, the muffler must really be restrictive if the sound if this quiet."

First impressions with part-throttle driving was that it felt 'smoother' and more relaxed. I noticed I could do highway speed passes without the trans kicking down a gear at roughly the same acceleration rate.

I then went to the drag strip to confirm any gains. Unfortunately, the car had about 3/4 tankful, compared to my baselline runs which were done at 1/8 tankful. To top it off, the temperatures differed by 20 degrees.

So to compensate, I removed the spare tire and tools to minimize the weight difference. I also added 1 mph to my base times to help equalize the temperature difference.

So my baseline traps were corrected to 91 mph. After the catback install, I trapped at 92.5 mph on average. So at first glance, it looks like I did pick up about 10-15 HP.

Since my 'correction factors' are NOT scientific. I measured gas mileage as a back up ( I do this anyways with all my cars).

If the exhaust makes more HP, it does so by increasing exhaust flow, thus increasing engine efficiency. If my catback did make more HP, I should see an INCREASE in mpg.

After one month, my average went up to 18.3 mpg. Before this, I averaged 17.5 mpg (using data from similar temperatures).

This equates to a 4.5 % increase. The HP improvement should be similar in terms of %. Using a baseline of 315 HP, this comes out to 14 HP. This number backs up the mph gain I saw at the track.

Again, this is NOT scientific at all. But at least the increase in gas mileage and the increase in trap speeds do correlate with one another.
 

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beat you... 13.1 :D
 
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