Top Speed Pro-1 Catback Exhaust HP Increase
 

Since a lot of 986Forum owners seem have the Top Speed Pro 1 catback exhaust, I thought I'd publish my results (before and after dyno runs).

1999 2.5L base engine, 135000 miles, underdrive pulley, LWFW, spec clutch, otherwise completely stock. ONLY the catback exhaust was installed, stock headers and cat's still installed (early cars like this only have one cat per side). No cat delete pipes. Nothing else was changed between the two runs.

Each major vertical gridline is 10 hp. Lefthand vertical axis (HP) not labeled for competitive reasons. A/F Ratio scale has been adjusted.

The green line is the stock muffler, the red line is the Top Speed Pro 1. The squiggly red line is the A/F ratio with the Top Speed exhaust. We did not measure A/F ratio with the stock muffler (other green line is flat).

Net result: +7hp @ 6150rpm. Peak +2 hp. All of the gains come above 5800 rpm. No appreciable difference in hp up to 5800.

I find the sound of the Top Speed catback to be awesome throughout the entire RPM range, though sound preference is subjective. The Top Speed exhaust also saves 18 lbs in weight. For $315, its a great deal.

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I bought an ebay exhaust from Beluga Racing (probably the same manufacturer as the Top Speed, different marketing) and have a question for you.

On a cold start, I get a popping noise for the first minute or so, kind of like popcorn popping. It's actually kind of annoying because it doesn't really sound like an aggressive gurgle, more of a cheap popping sound. Are you experiencing the same? I have about a few thousand miles (less than 1 year) on the exhaust now.

I have not experienced anything like that (yet).

Tom, thats great validation that the muffler does more than just sound nice.

Popcorn? I know if I rev up high that there is the gurgle/pop sounds as the revs come back down, or when down shifting agressively.


Maybe you have grass hoppers in your muffler that are getting cooked...thats strange and not something I have experienced with my TS either.

Thanks for posting Tom,

The results are about what one might expect. A slight bump in hp at the highest revs for those long straights. Interesting seeing the sine wave in your A/F ratio from 5-6k with no corresponding fluctuation in hp. Not a lot of tuning options with 5.2 software in a spec class. A torque curve comparison might also be useful.

I need to do this on my car now.

I thought who he must be obeyed said most aftermarket exhausts lose as much as 15hp...

If it happens when you are driving it is a backfire. (generally while decel in gear) My exhaust does this, granted I am sure much more so than yours. Unless you have catless headers and midpipes with a AM exhaust as well.

This might be similar to what I get with the Top Speed. I've always thought it was an exhaust rattle until things heat up a tiny bit. Maybe 5-10 seconds if I give it any gas off idle. Does not sound like it's coming from the engine. Sounds kind of like popcorn, as you described. Doesn't do it at idle.

I don't get anything like that at start up with my TS. I do get the popping at deceleration which I love hearing:cool:

Yes, it's odd. It does it on start up at idle and takes maybe 20 seconds to go away. I feel like it has something to do with warming up as well because it doesn't do it on a warm start or when I idle at a light, only on a cold start.

I also get the gurgle on decel, but this is a different sound. I'll try and post up a video when I have some time and create a new post. Sorry for the OTness.

Back on topic: awesome news that we are getting gains with the exhaust! =)

Actually, I need to thank you since I decided that the TS Pro 1 was the right exhaust after you shared your experience with me when we talked Boxster's at the California Festival of Speed. :cheers: