Q: What catalyst should I choose?
A: The right catalyst depends on how you use your vehicle—whether you plan to tune it, do track days, or need to meet emissions requirements specific to your country or state. If you are not tuning or want a check engine light (CEL) free setup, we have created a detailed CEL Free Guide based on extensive testing and experience. You can view it [here].
We use top-tier catalytic converters from HJS (Germany) and Gesi (Canada). HJS catalysts have a 200 cpsi (cells per square inch) rating, while Gesi uses 400 cpsi for improved emissions on newer models. We always select the largest catalyst that fits the space available to maximize flow and power potential—something many competitors don’t disclose, often using smaller, unbranded cats. If you want a different size than what’s listed, just ask.
HJS: Made in Germany, these 200-cell ultra-high performance catalysts offer around 93% flow efficiency versus a straight pipe. Euro6-rated and EPA-compliant, they support up to 1200 hp and come in 121mm, 130mm, and 143mm sizes.
GESI: Canadian-made GEN2 catalysts have 400 cells, flow roughly 85%, and comply with EPA standards. They handle 850–1200 hp depending on size and are available in 4.5”, 5”, and 6”.
Q: What is the heat shielding option and do I need it?
A: Our proprietary thermal heat shielding features a 5-8mm ceramic wool layer wrapped in precision-formed stainless steel foil, installed using 3D-printed molds for a perfect fit. This setup cuts temperatures by over 50%, outperforming typical wraps or coatings others use. Heat shielding without a ceramic wool air gap is ineffective, which is common with cheaper products.
We highly recommend adding heat shielding, especially for downpipes that connect directly to the turbo or pass through the transmission tunnel. It helps keep turbo and intake air temperatures down, reduces heat soak, and prevents timing retards, improving performance and reliability.
Additionally, it smooths the exhaust note and reduces cabin vibrations (NVH), making your driving experience more refined.
Q: How do I use the tunable O2 spacer?
A: The O2 spacer is installed on the downstream (post-catalyst) oxygen sensor bung and comes with three inserts (“pills”) for tuning flexibility. Start with the medium-sized insert and reset your ECU before driving with a OBD reader. If no CEL appears after driving, you’re good. If a CEL does appear, switch to a larger or smaller insert and repeat.
A low efficiency code means the insert is too large.
A slow response or rich-to-lean code means the insert is too small.
Note: Please contact your preferred tuner, typically O2 spacers are NOT necessary if you have a proper Stage 2 ECU tune.
Q: Do I need new gaskets?
A: When installing exhaust components, it’s best to use new gaskets for a proper seal. Stainless steel double-wall flat gaskets can sometimes be reused if in good condition, but we recommend replacing them if your vehicle has over 40-50K miles. OEM gaskets fit all Redstar products.
Q: What is OPF and how do I know if my vehicle has it?
A: OPF (Otto Particulate Filter) is a particulate emissions filter required in places like Europe and Australia on many vehicles from 2020 onward. Downpipes for OPF-equipped cars often have extra thermocouples and pressure sensors, sometimes on midpipes too. Because of these sensors, tuning is usually required (about 90% of cases). Our products have extra bungs for all OEM sensors to ensure easy fitment.
If you’re unsure whether your vehicle has OPF, please provide your VIN before ordering.
Q: What pipe sizes do you use?
A: With over 10 years of experience, we use various pipe diameters (e.g., 4”, 3.5”, 3”, 2.5”) chosen specifically for each application, not a one-size-fits-all approach. Remember, bigger isn’t always better—optimal power requires careful sizing and design.
Q: Who do you recommend for tuning with your downpipes?
A: We highly recommend Eurocharged for ECU and TCU tuning. We’ve partnered with them since 2017 and have seen excellent results.
Contact Eurocharged at eurocharged.com or call +1-713-462-1600.
Q: How do I check if an item is in stock or get a build time?
A: Visit our up-to-date inventory page [here]. It’s regularly updated, but always contact us to confirm availability or get a quoted build time.
Q: Will I have to pay customs duties, taxes, or tariffs?
A: Import fees, duties, or taxes may apply depending on your country’s regulations. We cannot calculate or control these charges. We declare shipment values as low as possible to help reduce fees. Redstar Exhaust is not responsible for customs charges or taxes, and returns will not be accepted due to these fees.
Q: What is Inconel 625 and why use it in exhausts?
A: Inconel 625 is a nickel-based superalloy prized for:
Superior corrosion resistance against moisture and exhaust gases
High strength at extreme temperatures, ideal for turbocharged engines
Durability and long lifespan, reducing replacements
Lightweight design without sacrificing strength
Excellent resistance to thermal fatigue from rapid heat cycles
Chemical resistance to exhaust gases
Unique sound characteristics appreciated by enthusiasts
Inconel 625 ensures exhaust components remain reliable and perform well in demanding track conditions.
Q: What is Titanium and why use it in exhausts?
A: Titanium offers:
Significant weight savings over steel, improving handling and efficiency
High-temperature strength for durability in hot exhaust environments
Excellent corrosion resistance, extending exhaust life
Longevity and reduced maintenance
A distinctive, often rainbow-hued finish when heated, valued for aesthetics
Unique sound characteristics appreciated by enthusiasts
Titanium is ideal for high-performance sports cars where lightweight and durability matter.
If you need further assistance or have more questions, feel free to contact us anytime!