A solution for unwanted drone and rasp with all of the benefits of a test pipe
I recently installed an HKS Dual Resonated Front Pipe because my exhaust set up has been filled with obstacles and headaches. The short version of my issues is that my catless/unresonated Invidia front pipe sounds raw and super aggressive, but is way too raspy when paired with a catless header (see comparison video below). The stock front pipe has no rasp at all, but leaks no matter how I try to remedy it. The tone with the factory front pipe is also way less aggressive and sounds a bit corked. Weirdly, interior drone is also way higher than with my Invidia front pipe.
The options to solve my problem were the following:
- Buy an aftermarket front pipe with a high-flow cat - The issue with this option is that catted front pipes are expensive, and I've already spent money on 1 aftermarket front pipe.
- Buy an uncatted, resonated front pipe - The issue here is that most resonated front pipes have 1 resonator, which may not be enough to eliminate all of the rasp
- Buy the HKS front pipe. It's uncatted, so it's reasonably priced. It also has 2 resonators instead of 1, so it should remove more rasp than other resonated front pipes (in my mind). In theory, the HKS pipe is a win-win
I decided to roll the dice on the HKS front pipe, and I'm very happy that I did. The overall tone is just as aggressive as the unresonated front pipe, but there's virtually no rasp at any RPM. Interior drone is also about as low as can reasonably be expected, and there are no exhaust leaks. I highly recommend this front pipe to anyone who likes a loud exhaust, prefers the raw sound of an uncatted exhaust, and dislikes rasp.
- The welds and flange thickness are a little bit dissapointing. Comparing my Tomei header, Greddy cat back, and Invidia front pipe to the HKS front pipe, it seems a bit less beefy and cheap. The welds are a little sloppier. The flanges are thinner, and the HKS doesn't have any nice looking etching or engraving
- Fitment is perfect. Everything lines up exactly how it was supposed to
- Despite the welds and flanges, it's done absolutely everything that I hoped it would. As long as it holds up, the welds and flanges are easily forgiven
Resonated Vs Unresonated Front Pipes
One of the most difficult things about buying exhaust compenents is that unless you know someone with the exact combination that you're looking for, there's no way to know exactly how each piece is going to impact tone, volume, and overall sound.
One question that I'd always had about the front pipe is how much of an impact does a resonator have on rasp and drone in the front pipe? To completely eliminate rasp, is a catalytic converter needed? I gambled on buying the HKS front pipe without knowing if it would solve what I was hoping to fix. I wanted to maintain an aggressive sound, maximize power by remaining catless, and eliminate the rasp that I absolutely could not live with with my uncatted and unresonated front pipe. Fortunately, it worked. To help others answers these questions without making multiple purchases, I made a video comparing the sound of my Invidia unresonated front pipe vs the HKS dual resonated front pipe. The only variable between the videos is the front pipe. The rest of the exhaust set up in both videos was a Tomei UEL catless header, stock over pipe, and Greddy Revolution RS cat back.