After outfitting Associate Editor Frank Cicerale's '98 Z28 with a Textralia clutch and B&M shifter back in the April '07 issue, we thought it was finally time to start throwing some power at it. The Z's only modest upgrades beforehand were an air lid and a catback exhaust, with the stock manifolds and Y-pipe still having a stranglehold on the exhaust. To get things moving we gave Dynatech a call for a set of SuperMAXX long-tube headers (p/n 115-732300A) and Y-pipe with high-flow cats (p/n 115-732300B). With T-304 stainless steel throughout, 3/8-inch flanges, quality welds, a 1.75-inch long-tube design, and dual PowerCats that flow 396.4 cfm, these headers are hard to beat. We've had good luck with them in the past, as have several shops I've spoken to, given their excellent fit and overall quality-let alone performance. When we arrived at East Side Performance to do the install, I was surprised to find out that the crew had put a set of Dynatechs on its 8-second LSX-based Hugger Orange Camaro.
Since the previously installed catback had a straight-through bullet muffler, we opted to trade it in for a more traditional design that would make Raceway Park-and Frankie's neighbors-a little happier. As one of the leaders in sound cancellation technology, we had every confidence in Corsa Performance to deliver a top-quality, high-performing system with little droning and a great tone. The 304-stainless steel, mandrel-bent tubing combined with the Power-Pulse RSC technology muffler successfully eliminate restriction from the exhaust without sacrificing emissions legality. In addition, Corsa makes some of the best exhaust tips in the business. We went with the Single Pro-Series 4.0 Tips (p/n 14148), though the Dual Pro-Series 3.5 Tips (p/n 14143) would not have been a bad choice either.
To dial in the new exhaust system, we decided to have East Side Performance tweak the fuel enrichment and spark advance while the Z was strapped down to East Side's in-house Dynojet. Since we would be using the opportunity to also tweak a few of the LS1 computer's other parameters such as the radiator fan operation, upgrading to a 160-degree thermostat was also recommended. SLP Performance Parts was more than happy to send over its 160-degree LS1 Thermostat (p/n 100223) to replace the factory 195-degree piece and allow the coolant to circulate at a lower temperature. This quick and simple $60 upgrade has proven to add a few ponies on the dyno, and will be a valuable investment with more modifications on the way. Though our test car is still hampered by the factory LS1 intake and un-ported throttle body, the short list of bolt-ons and custom tune should easily be a 20hp improvement ... but to find out you'll have to follow along.
On East Side Performance's Dynojet our '98 Camaro tester previously recorded 303.3 hp and 318.6 lb-ft with an air lid and catback. However, with the addition of the Dynatech headers and Corsa catback, AFR went from low to high 13:1 with the stock tune. Since '98s have 28 degrees of timing stock, Alfred had only to play with the fuel enrichment tables to safely make 328.0 hp and 339.6 lb-ft. At the track, Frank managed to improve on his previous 13.91 with a 13.57. For argument's sake we had another driver pilot the Z (before and after), which yielded an improvement of two tenths (13.55 to 13.35). Both improvements, though, seem consistent with a gain of nearly 25 hp.