{"product_id":"m8-touring-big-bore-series","title":"M8 Series","description":"\u003ch3 data-end=\"365\" data-start=\"330\"\u003eNEW FOR 2026!\u003c\/h3\u003e\n\u003ch3 data-end=\"365\" data-start=\"330\"\u003eM8 SERIES EXHAUST SYSTEM w\/ \u003cspan\u003e Indexable Cylinder Backpressure Technology.\u003c\/span\u003e\n\u003c\/h3\u003e\n\u003cp data-end=\"804\" data-start=\"367\"\u003e\u003cspan data-end=\"519\" data-start=\"484\"\u003eThe\u003c\/span\u003e\u003cstrong data-end=\"519\" data-start=\"484\"\u003e M8 Series Exhaust System\u003c\/strong\u003e is a purpose-engineered exhaust platform designed around high-output, big-inch Harley-Davidson® V-twin engines. Every design decision prioritizes exhaust gas velocity, cylinder balance, and high-horsepower stability—eliminating the compromises found in generic large-diameter systems.\u003c\/p\u003e\n\u003cp data-end=\"1040\" data-start=\"806\"\u003eEngineered for \u003cstrong data-end=\"874\" data-start=\"821\"\u003e124–143ci+ Milwaukee-Eight platforms\u003c\/strong\u003e, the \u003cstrong\u003eM8\u003c\/strong\u003e \u003cstrong\u003eSERIES\u003c\/strong\u003e can be configured to support \u003cstrong data-end=\"948\" data-start=\"921\"\u003e240+ horsepower\u003c\/strong\u003e while maintaining precise control over exhaust pulse timing and scavenging characteristics.\u003c\/p\u003e\n\u003ch3 data-end=\"1078\" data-start=\"1042\"\u003eTwo Size-Specific Configurations\u003c\/h3\u003e\n\u003cp data-end=\"1262\" data-start=\"1080\"\u003eThe \u003cstrong\u003eM8 Series\u003c\/strong\u003e is offered in \u003cstrong data-end=\"1152\" data-start=\"1122\"\u003etwo primary tube diameters\u003c\/strong\u003e, allowing the exhaust to be properly matched to engine displacement, airflow demand, and operating RPM range:\u003c\/p\u003e\n\u003ch2 data-end=\"1284\" data-start=\"1266\"\u003e\n\u003cstrong\u003e\u003c\/strong\u003e\u003cbr\u003e\n\u003c\/h2\u003e\n\u003ch2 data-end=\"1284\" data-start=\"1266\"\u003e\n\u003cstrong\u003e131 Series:\u003c\/strong\u003e\u003cbr\u003e\n\u003c\/h2\u003e\n\u003cp data-end=\"463\" data-start=\"141\"\u003eEngineered for riders who demand strong, usable power, these step tuned headpipes are designed to maximize exhaust efficiency where it matters most. The progressive diameters increase in precisely calculated steps from\u003cstrong\u003e 1.87\" to 2.00\" to 2.12\"\u003c\/strong\u003e in order to maintain higher exhaust gas velocity, helping build hard-hitting midrange torque and crisp throttle response.\u003c\/p\u003e\n\u003cp data-end=\"722\" data-start=\"465\"\u003eOptimized for engines\u003cstrong\u003e 124-131\u003c\/strong\u003e\u003cstrong data-end=\"513\" data-start=\"493\"\u003e cubic inches\u003c\/strong\u003e, this design balances flow and velocity to deliver smooth power delivery without sacrificing low- and mid-RPM performance. Ideal for high-performance builds looking for stronger pull and improved rideability.\u003c\/p\u003e\n\u003cp data-end=\"1466\" data-start=\"1378\" style=\"text-align: left;\"\u003e \u003c\/p\u003e\n\u003ch2 style=\"text-align: left;\" data-end=\"1466\" data-start=\"1378\"\u003e\n\u003cbr\u003e\u003cstrong\u003e135+ Series\u003c\/strong\u003e\n\u003c\/h2\u003e\n\u003cp data-end=\"1523\" data-start=\"1494\"\u003eBuilt for extreme displacement and high-RPM performance, the \u003cstrong data-end=\"212\" data-start=\"197\"\u003e135+ Series\u003c\/strong\u003e is engineered to handle the massive exhaust volume demanded by today’s biggest V-twin builds. Featuring a progressive step-tuned design that expands from \u003cstrong data-end=\"400\" data-start=\"367\"\u003e1.87\" → 2.00\" → 2.12\" → 2.25\"\u003c\/strong\u003e, this system maximizes flow while maintaining control over exhaust velocity where it counts.\u003c\/p\u003e\n\u003cp data-end=\"1523\" data-start=\"1494\"\u003eDesigned specifically for \u003cstrong data-start=\"521\" data-end=\"549\"\u003e135ci and larger engines\u003c\/strong\u003e, the added final step supports high airflow at elevated RPM, helping big-inch motors breathe freely and pull hard without restriction. The result is a system optimized for peak performance in aggressive, high-output applications.\u003c\/p\u003e\n\u003cp data-end=\"1955\" data-start=\"1687\"\u003e\u003cbr\u003eBoth \u003cstrong\u003e131 \u003c\/strong\u003eand \u003cstrong\u003e135+ \u003c\/strong\u003esystems share \u003cstrong data-end=\"1769\" data-start=\"1706\"\u003eidentical routing, collector placeme\u003c\/strong\u003e\u003cstrong data-end=\"1769\" data-start=\"1706\"\u003ent, and chassis fitment\u003c\/strong\u003e, ensuring consistent installation and clearance. The only difference is the \u003cstrong data-end=\"1879\" data-start=\"1846\"\u003eprimary exhaust tube diameter\u003c\/strong\u003e, allowing airflow to be scaled correctly without altering exhaust geometry.\u003c\/p\u003e\n\u003cp data-end=\"1955\" data-start=\"1687\"\u003e \u003c\/p\u003e\n\u003ch3 data-end=\"2006\" data-start=\"1957\"\u003eAdvanced Exhaust Control\u003c\/h3\u003e\n\u003cp data-end=\"2398\" data-start=\"2008\"\u003eEach system can feature \u003cstrong data-end=\"2075\" data-start=\"2029\"\u003eIndexable Cylinder Backpressure Technology\u003c\/strong\u003e, allowing \u003cstrong data-end=\"2167\" data-start=\"2086\"\u003eeach individual headpipe to be tuned independently before the merge collector\u003c\/strong\u003e. This enables precise balancing of cylinder-to-cylinder exhaust pressure, improving combustion efficiency, reducing reversion, and stabilizing air\/fuel ratios under load—critical for large-displacement and high-compression builds.\u003c\/p\u003e\n\u003ch3 data-end=\"2006\" data-start=\"1957\"\u003e\u003cbr\u003e\u003c\/h3\u003e\n\u003ch3 data-end=\"2006\" data-start=\"1957\"\u003eThermal Management\u003c\/h3\u003e\n\u003cp data-end=\"2664\" data-start=\"2400\"\u003eThese exhaust systems are offered with optional \u003cstrong data-end=\"2468\" data-start=\"2429\"\u003efull-length, one-piece heat shields\u003c\/strong\u003e, providing uniform thermal coverage while eliminating visual breaks. This design improves heat management, long-term durability, and delivers a clean, uninterrupted appearance.\u003c\/p\u003e\n\u003cp data-end=\"2664\" data-start=\"2400\"\u003e \u003c\/p\u003e\n\u003ch3 data-end=\"2706\" data-start=\"2666\"\u003eBuilt for Extreme V-Twin Performance\u003c\/h3\u003e\n\u003cp data-end=\"3004\" data-start=\"2708\"\u003eThe \u003cstrong\u003eM8\u003c\/strong\u003e \u003cstrong\u003eExhaust System\u003c\/strong\u003e is not simply oversized—it is \u003cstrong data-end=\"2808\" data-start=\"2774\"\u003eengineered to scale with power\u003c\/strong\u003e. From displacement-specific primary sizing to indexable backpressure control, this system is designed for builders and riders pushing Harley-Davidson V-twin performance far beyond factory limits.\u003c\/p\u003e\n\u003cp data-end=\"3634\" data-start=\"3500\"\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Steel City Cycle LLC","offers":[{"title":"Up to 131ci \/ Brushed Stainless (Standard) \/ No Heatshields (+$0)","offer_id":48000287309979,"sku":null,"price":2250.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Brushed Stainless (Standard) \/ Full Length Heatshields (+$300)","offer_id":48000287342747,"sku":null,"price":2550.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Mirror Polished \/ No Heatshields (+$0)","offer_id":48000287375515,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Mirror Polished \/ Full Length Heatshields (+$300)","offer_id":48000287408283,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Cerakote Black \/ No Heatshields (+$0)","offer_id":48000287441051,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Cerakote Black \/ Full Length Heatshields (+$300)","offer_id":48000287473819,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Cerakote Dark Bronze \/ No Heatshields (+$0)","offer_id":48000287506587,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Cerakote Dark Bronze \/ Full Length Heatshields (+$300)","offer_id":48000287539355,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Cerakote Gold \/ No Heatshields (+$0)","offer_id":48000287572123,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Cerakote Gold \/ Full Length Heatshields (+$300)","offer_id":48000287604891,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Cerakote Silver \/ No Heatshields (+$0)","offer_id":48000287637659,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"Up to 131ci \/ Cerakote Silver \/ Full Length Heatshields (+$300)","offer_id":48000287670427,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Brushed Stainless (Standard) \/ No Heatshields (+$0)","offer_id":48000287703195,"sku":null,"price":2250.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Brushed Stainless (Standard) \/ Full Length Heatshields (+$300)","offer_id":48000287735963,"sku":null,"price":2550.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Mirror Polished \/ No Heatshields (+$0)","offer_id":48000287768731,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Mirror Polished \/ Full Length Heatshields (+$300)","offer_id":48000287801499,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Cerakote Black \/ No Heatshields (+$0)","offer_id":48000287834267,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Cerakote Black \/ Full Length Heatshields (+$300)","offer_id":48000287867035,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Cerakote Dark Bronze \/ No Heatshields (+$0)","offer_id":48000287899803,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Cerakote Dark Bronze \/ Full Length Heatshields (+$300)","offer_id":48000287932571,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Cerakote Gold \/ No Heatshields (+$0)","offer_id":48000287965339,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Cerakote Gold \/ Full Length Heatshields (+$300)","offer_id":48000287998107,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Cerakote Silver \/ No Heatshields (+$0)","offer_id":48000288030875,"sku":null,"price":2650.0,"currency_code":"USD","in_stock":true},{"title":"135ci+ \/ Cerakote Silver \/ Full Length Heatshields (+$300)","offer_id":48000288063643,"sku":null,"price":2950.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0679\/0542\/1467\/files\/rn-image_picker_lib_temp_51dc24bb-6caf-44cf-96d2-63512d2f965e.jpg?v=1769799859","url":"https:\/\/steelcitycc.com\/products\/m8-touring-big-bore-series","provider":"Steel City Cycle LLC","version":"1.0","type":"link"}