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Description
1999-2000 Mazda Miata MX5 1.8L 4-2-1 SS 1-5/8 Header XForce HS-9918Enhance Your Mazda MX 5's Performance with the XForce 4 2 1 Stainless Steel Header Upgrade your 1999 2000 Mazda MX 5 Miata's exhaust system with the XForce 4 2 1 Stainless Steel Header (Part Number: HS 9918). This high quality header is engineered to improve exhaust flow, resulting in enhanced engine performance and a more responsive driving experience. Key Features: Tri Y Design: The 4 2 1 configuration optimizes exhaust scavenging, leading to
Enhance Your Mazda MX-5's Performance with the XForce 4-2-1 Stainless Steel Header
Upgrade your 1999-2000 Mazda MX-5 Miata's exhaust system with the XForce 4-2-1 Stainless Steel Header (Part Number: HS-9918). This high-quality header is engineered to improve exhaust flow, resulting in enhanced engine performance and a more responsive driving experience.
Key Features:
- Tri-Y Design: The 4-2-1 configuration optimizes exhaust scavenging, leading to increased horsepower and torque across the RPM range.
- Stainless Steel Construction: Made from durable 304 stainless steel, this header offers excellent corrosion resistance and longevity.
- Precision Engineering: Mandrel-bent tubing ensures smooth exhaust flow, while CNC-machined flanges provide a secure, leak-free fit.
- Fuel Type: Gasoline
- California Prop 65 Warning: This product may contain chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm.
Specifications:
- Brand: XForce
- Type: Exhaust Header
- Items Included: Header, Gaskets, Mounting Hardware
- Material: 304 Stainless Steel
- Substrate Material: Stainless Steel
- Primary Tube Diameter: 1 5/8 inches
- Header Style: Tri-Y (4-2-1) One-Piece Design
- Collector Attachment: 2-Bolt Flange
- Finish: Natural Stainless Steel
- Features: Mandrel-Bent Tubing, CNC-Machined Flanges, Bolt-On Installation
- Fuel Type: Gasoline
- Placement on Vehicle: Front (Engine Bay)
- Manufacturer Part Number: HS-9918
- OE/OEM Part Number: HS-9918
Vehicle Compatibility:
This header is designed to fit the following Mazda MX-5 Miata models:
- 1999-2000 Mazda MX-5 Miata: 1.8L 4-cylinder engine
Note: While some references indicate compatibility with 1998-2005 models, it is recommended to verify fitment for models outside the 1999-2000 range.
Items Included:
- XForce 4-2-1 Stainless Steel Header (HS-9918)
- Gaskets
- Mounting Hardware
Installation Notes:
- Professional Installation Recommended: Due to the complexity of exhaust system modifications, professional installation is advised to ensure optimal performance and fitment.
- No Welding Required: Designed for a bolt-on installation using standard hand tools.
- Complete Kit: Includes all necessary gaskets and mounting hardware for a complete installation.
Upgrade your Mazda MX-5 Miata's exhaust system with the XForce HS-9918 header to experience improved performance, durability, and a more exhilarating driving experience.
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.1 ★★★★★
Based on 15 reviews
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Product Reviews
★★★★★ 5
DERM APPROVED!
I am obsessed with this product!! This feels very luxurious on my skin and does not pill like other products I have had in the past. I have noticed a significant improvement in the background redness in my skin. As someone who works in derm and values good ingredients and products that actually work... I can confidently say that this is the best OTC azelaic acid product I have tried out. It sits very nicely under my moisturizer and does not dehydrate my skin like other azelaic acid products have done in the past. HIGHLY RECOMMEND
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 10, 2026
★★★★★ 5
A Game Changer for Sensitive Skin
I use this serum every single day, and it has become one of the most important products in my skincare routine. I have very sensitive skin and cannot tolerate stronger active ingredients such as retinol or high-strength acids, so finding something effective but gentle has been incredibly important.
This serum has helped calm redness, reduce inflammation, and noticeably improve my skin’s overall appearance and comfort. After dealing with a prolonged inflammatory skin condition, this product made a significant difference and helped restore my skin barrier.
The formula feels soothing, hydrating, and non-irritating. If you have sensitive or reactive skin and are looking for a gentle product to help with redness and uneven texture, I highly recommend giving this serum a try.
Photos attached: The green bottle is the product and the second photo includes my favorite additions.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 13, 2026
★★★★★ 5
Perfect for Acne-Prone Skin!
This serum has honestly been a great addition to my routine for redness and post-acne marks. The texture is lightweight, hydrating, and doesn’t feel sticky or heavy on my oily/acne-prone skin.
I have sensitive skin with a focus on barrier protection, and this didn’t irritate my skin at all. It layers beautifully with the rest of my skincare and leaves my skin looking calmer and smoother over time. AND, it doesn’t have a smell!!
Definitely one of my favorite azelaic acid serums I’ve tried.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 18, 2026
★★★★★ 5
6-Month Update: Still a staple for sensitive, acne-prone skin
Size: 3.38 Fl Oz (Pack of 1), Size: 3.38 Fl Oz (Pack of 1)
I originally reviewed this ampoule when I first started using it, and now after about six months of consistent use (morning and night), I feel confident giving a more long-term update.
I have sensitive, acne-prone, combination skin, and this has remained one of the most reliable products in my routine. The texture is still one of my favorite things about it — very lightweight, absorbs quickly, and layers well under moisturizer and sunscreen without pilling.
Over time, I’ve noticed:
Less visible redness
More balanced oil production in my T-zone
Fewer irritation flare-ups when introducing new products
No clogged pores or breakouts from this formula
It doesn’t feel heavy or sticky, even in humid weather. I’ve continued repurchasing and even keep it on subscription because it consistently performs without causing sensitivity.
If you’re looking for a gentle, soothing centella product that works well for long-term barrier support, this has proven to be a dependable option in my experience.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 9, 2025
★★★★★ 5
Healed my barrier so fast
Size: 3.38 Fl Oz (Pack of 1)
I received this ampoule yesterday and I'm already leaving a 5 star review after 2 uses because it just worked so well. I bought it because I've recently incorporated the Timeless 20% Vitamin C into my routine and that + my tretinoin made my skin drier than I've ever felt it before, even gently swiping a cotton pad with micellar would sting on some parts of my face. As soon as this ampoule arrived I applied it to clean skin and layered squalane on top (my moisturizer was burning as well.) This product did not sting my face AT ALL. It instead felt immediately soothing and hydrating. When I woke up this morning almost all of my redness was gone, my skin didn't feel tight or irritated, and my skin tone looked so even and glowy. I never thought a product, especially such a simply formulated one, could heal my barrier so quickly but that's exactly what it did and I can already tell it's a repeat buy. If you have redness prone sensitive skin and/or you use several high strength actives, this ampoule is a must have and it might be the key for anyone struggling to tolerate high strength retinoids. I got the largest size bottle for $15 on sale and it's seriously one of the most affordable and effective skincare products I've ever had in my routine.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 30, 2026
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