Blog
MagnaFlow OEM-Grade vs CARB-Grade: Which Catalytic Converter Is Legal in Your State?
OEM-Grade, HM-Grade, Standard and CARB-Grade MagnaFlow converters explained, with the state rules for California, Colorado, New York and Maine. Learn when the EPA lets you replace a converter and which grade keeps...
do88 Buyers Guide: What the Swedish Cooling Brand Is, and Which Part to Buy First
What do88 is, what its premium buys, and which do88 part to buy first on the N54, N55, S55, B58, S58 and E9x M3, with prices and owner reports.
APR Intake Guide: Which Intake Fits Your VW or Audi, and What You Actually Gain
Which APR intake fits your GTI, Golf R, A3, S3, B9 S4 or S5, or RS3, and what it really adds on a turbo engine. APR's own flow data shows why the...
H&R Wheel Bolt Guide: The Right Bolts for Your Wheel Spacers
H&R TRAK+ DR spacers need longer wheel bolts sold separately, and the bolt must match your thread, your wheel's seat and the spacer thickness. Here is H&R's length rule, seat codes and...
Coilovers vs Lowering Springs: Which Is Right for You?
Coilovers vs lowering springs for BMW, Audi, Supra, GTI and Mustang: prices from $330 to $4,094, drop figures, adaptive damper rules and our pick per car.
Bilstein B12 vs B14 vs B16: Which Suspension Kit Should You Buy?
Bilstein B12 vs B14 vs B16 compared for BMW F30, E46, M3, Audi S4, GTI, Mustang and GR86: lowering, 10 click damping, warranty, US prices and owner reports.
H&R vs Eibach Lowering Springs: Which Drop Is Right for Your BMW?
H&R Sport and Eibach Pro-Kit compared on 14 BMW fitments with each maker's own drop figures, plus the xDrive and trim part number traps and the spring we would buy for each...
KW Coilovers: Which One Should You Buy?
KW's V1, V2, V3, Clubsport, DDC and HAS lines compared by damping adjustment, warranty, adaptive damper handling and price, with owner reports and a pick for popular BMW, Audi and Supra models.
Walbro 450 vs 535 vs DW400: Which Fuel Pump Do You Need?
Walbro 450 vs 535 vs DW400 compared on flow at 40 to 100 psi, amp draw, E85, check valves and US dollar prices, with what N54 and Mustang owners report.