Most people think that cat-back exhausts don’t offer substantial power. When compared to a turbo-back exhaust, no, but axle-backs DO offer torque. The thing is, most tuners don’t test for this and just make blatant assumptions.
Well, there’s at least one parts manufacturer that does test axlebacks: Nameless Performance.
Here’s what I saw a year ago on their Facebook page:
That car gained 30 ft-lb of torque. That’s rather significant, especially considering that this car wasn’t tuned…they just bolted on a catback and dyno’d it! And if you haven’t looked at the comments within that FB post, take a look:
FB User: Wow…that’s a very good gain for just a catback! And without a tune! Says a lot about the stock parts…LOL! Nameless should post that up at IWSTI, because all I ever hear there is that catback exhausts don’t add performance. Now, will GRs have a similar gain? I’ve the axleback…makes me want to replace some more bits.
Nameless Performance, Inc.: Well that’s some bs from what we’ve seen on our design – unless there is some serious shortcoming on other companies exhausts. I know our downpipe thumps on the competition for torque gains, but this was just a cbe with a stock downpipe and no tune. Will have more data forthcoming on full turboback with OTS S2 as well as our specific OTS S2 tune for these cars. Think we can hit 70ft lb? We shall see. Downpipe goes on tomorrow.
FB User: I’m quite happy with the CBE results, since I’m currently trying not to mod the engine. Maybe the other companies exhausts DO have shortcomings, but you guys just proved to me that, sometimes, internet forums are a crock of shit. I’m sure you can hit 70 ft/lb, because you’re almost halfway there already!
Nameless Performance, Inc.: Yeah I mean the total numbers on this CBE for peak HP gain are 12hp, but we make 17hp at 3100RPM and 29.5 ft lb at the same RPM range. I honestly think it’s a situation where CBE manufacturers don’t do the testing for the most part, so they don’t have any information to share which leads to people having to assume low power gains due to no advertised dyno results. I do think this one is particularly good, however.
FB User: How much gain on a 2011 wrx full catback ?
Nameless Performance, Inc.: 32ft lb / 22hp at the wheels for the ’11 Full Catback. That was dyno’d with a stage 1 ots tune for the baseline and no deviation from that tune on the equipped with cbe pull. This testing on the GD is stock vs. add CBE.
I thought I’d posted about this before, but I couldn’t find the post. It may’ve predated this blog. I also thought I’d seen a post referring to axle-back gains, but I’m still looking for that one (took me 50 minutes to find the first one).